EXHIBIT 4.8.4

SECOND AMENDMENT TO EXIM GUARANTIED CREDIT AGREEMENT

THIS SECOND
AMENDMENT TO EXIM GUARANTIED CREDIT AGREEMENT(this Amendment), dated as of March 25, 2011, is entered into by and among WELLS FARGO CAPITAL FINANCE, LLC, a Delaware limited liability company, formerly known as
Wells Fargo Foothill, LLC, as the administrative agent (in such capacity, Agent) for the Lenders (as defined below), the Lenders, STANADYNE INTERMEDIATE HOLDING CORP., a Delaware corporation (Parent), and
STANADYNE CORPORATION, a Delaware corporation (Borrower).

RECITALS

A. Borrower, Parent, the lenders party thereto from time to time (the Lenders) and Agent have previously entered into
that certain EXIM Guarantied Credit Agreement dated as of August 13, 2009 and amended as of August 31, 2010 (as the same may be modified, supplemented or amended from time to time, the Credit Agreement), pursuant to
which the Lenders have made certain loans and financial accommodations available to Borrower. Terms used herein without definition shall have the meanings ascribed to them in the Credit Agreement.

B. Borrower has requested that Agent and the Lenders amend the Credit Agreement which Agent and the Lenders are willing to do pursuant to
the terms and conditions set forth herein.

C. Borrower and Parent are entering into this Amendment with the understanding and
agreement that, except as specifically provided herein, none of Agents or any Lenders rights or remedies as set forth in the Credit Agreement are being waived or modified by the terms of this Amendment.

AGREEMENT

NOW, THEREFORE, in consideration of the foregoing and the mutual covenants herein contained, and for other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereby agree as follows:

1.
Amendments to Credit Agreement.

(a) The definition of Base Rate set forth in Schedule 1.1 of the Credit
Agreement is hereby amended and restated in its entirety to read as follows:

 Base Rate means the
greatest of (a) the Federal Funds Rate plus 0.50%, (b) the Base LIBOR Rate (which rate shall be calculated based upon an Interest Period of 3 months and shall be determined on a daily basis), plus 0.50%, and (c) the rate of interest
announced, from time to time, within Wells Fargo at its principal office in San Francisco as its prime rate, with the understanding that the prime rate is one of Wells Fargos base rates (not necessarily the lowest of
such rates) and serves as the basis upon which effective rates of interest are calculated for those



---

loans making reference thereto and is evidenced by the recording thereof after its announcement in such internal publications as Wells Fargo may designate.

(b) The grid contained in the definition of Base Rate Margin set forth in Schedule 1.1 of the Credit Agreement is hereby
amended and restated in its entirety to read as follows:



|       |  |                                                               |  |                        
|------ |  | ------------------------------------------------------------- |  | -----------------------
|Level |  | Borrowers Average Excess Availability                        |  | Base Rate Margin       
|       |  |                                                              
|I      |  | Less than $8,500,000                                          |  | 1.75 percentage points 
|       |  |                                                              
|II     |  | Greater than or equal to $8,500,000 but less than $11,000,000 |  | 1.50 percentage points 
|       |  |                                                              
|III    |  | Greater than or equal to $11,000,000                          |  | 1.25 percentage points

(c) Clause (i) of the definition of Eligible Accounts set forth in Schedule 1.1 of the Credit Agreement is hereby
amended and restated in its entirety to read as follows:

(i) (1) Accounts with respect to an Account Debtor (other than
Deere & Company, Ford Motor Company and Ford Werke AG) whose total obligations owing to Borrower exceed 15% (such percentage, as applied to a particular Account Debtor, being subject to reduction by Agent in its Permitted Discretion if the
creditworthiness of such Account Debtor deteriorates) of all Eligible Accounts, to the extent of the obligations owing by such Account Debtor in excess of such percentage; (2) Accounts with respect to Ford Motor Company and Ford Werke AG whose
total obligations owing to Borrower exceed 20% (such percentage being subject to reduction by Agent in its Permitted Discretion if the creditworthiness of such Account Debtors deteriorates) of all Eligible Accounts, to the extent of the obligations
owing by such Account Debtors in excess of such percentage, (3) Accounts with respect to Deere & Company whose total obligations owing to Borrower exceed 40% (such percentage being subject to reduction by Agent in its Permitted
Discretion if the creditworthiness of such Account Debtor deteriorates) of all Eligible Accounts, to the extent of the obligations owing by such Account Debtor in excess of such percentage; and (4) Accounts with respect to the five Account
Debtors and their Affiliates who have the highest total obligations owing to Borrower out of all other Account Debtors whose aggregate total obligations owing to Borrower exceed 80% of all Eligible Accounts, to the extent of the aggregate
obligations owing by such Account Debtors and their Affiliates in excess of such percentage; provided, however, that, in each case, the amount of Eligible Accounts that are excluded because they exceed the foregoing percentages shall
be determined by Agent based on all of the otherwise Eligible Accounts prior to giving effect to any eliminations based upon the foregoing concentration limits,



---

(d) The definition of Interest Period set forth in Schedule 1.1 of the Credit
Agreement is hereby amended and restated in its entirety to read as follows:

 Interest Period means,
with respect to each LIBOR Rate Loan, a period commencing on the date of the making of such LIBOR Rate Loan (or the continuation of a LIBOR Rate Loan or the conversion of a Base Rate Loan to a LIBOR Rate Loan) and ending 1, 2, or 3 months
thereafter, as selected by Borrower; provided, however, that (a) interest shall accrue at the applicable rate based upon the LIBOR Rate from and including the first day of each Interest Period to, but excluding, the day on which
any Interest Period expires, (b) any Interest Period that would end on a day that is not a Business Day shall be extended to the next succeeding Business Day unless such Business Day falls in another calendar month, in which case such Interest
Period shall end on the next preceding Business Day, (c) with respect to an Interest Period that begins on the last Business Day of a calendar month (or on a day for which there is no numerically corresponding day in the calendar month at the
end of such Interest Period), the Interest Period shall end on the last Business Day of the calendar month that is 1, 2, or 3 months after the date on which the Interest Period began, as applicable, and (d) Borrower may not elect an Interest
Period which will end after the Maturity Date.

(e) The grid contained in the definition of LIBOR Rate
Margin set forth in Schedule 1.1 of the Credit Agreement is hereby amended and restated in its entirety to read as follows:



|       |  |                                                               |  |                        
|------ |  | ------------------------------------------------------------- |  | -----------------------
|Level |  | Borrowers Average Excess Availability                        |  | LIBOR Rate Margin      
|       |  |                                                              
|I      |  | Less than $8,500,000                                          |  | 2.75 percentage points 
|       |  |                                                              
|II     |  | Greater than or equal to $8,500,000 but less than $11,000,000 |  | 2.50 percentage points 
|       |  |                                                              
|III    |  | Greater than or equal to $11,000,000                          |  | 2.25 percentage points

(f) The definition of Maximum Revolver Amount set forth in Schedule 1.1 of the Credit Agreement is hereby amended and
restated in its entirety to read as follows:

 Maximum Revolver Amount means, as of any date of
determination, $10,000,000, decreased by the amount of reductions in the Revolver Commitments made in accordance with Section 2.4(c) of the Agreement.

(g) The definition of Permitted Intercompany Investments set forth in Schedule 1.1 of the Credit Agreement is hereby amended and restated in its entirety to read as follows:



---

 Permitted Intercompany Investments means (a) loans made by
(i) a Loan Party to another Loan Party other than Parent or, (ii) a Non-Loan Party to another Non-Loan Party, (iii) a Non-Loan Party to a Loan Party, so long as the parties thereto are party to the Intercompany Subordination
Agreement, and (iv) a Loan Party to a Non-Loan Party so long as (1) no Default or Event of Default has occurred and is continuing at the time of such loan, and (2) the amount of outstanding loans made by all Loan Parties to all
Non-Loan Parties, when aggregated with Investments constituting contributions to capital made by all Loan Parties to all Non-Loan Parties does not exceed $16,000,000 (in each case other than Investments permitted by clause (e) of
Permitted Investments); and (b) Investments constituting contributions to capital made by a Loan Party in a Non-Loan Party, so long as (i) no Default or Event of Default has occurred and is continuing at the time of such
Investment, and (ii) the amount of Investments constituting contributions to capital made by all Loan Parties in all Non-Loan Parties, when aggregated with all outstanding loans made by all Loan Parties to all Non-Loan Parties, does not exceed
$16,000,000 (in each case other than Investments permitted by clause (e) of Permitted Investments).

(h) Schedule C-1 to the Credit Agreement is hereby amended and replaced with Schedule C-1 attached hereto.

2. Conditions Precedent to Effectiveness of this Amendment. This Amendment shall not become effective until all of the following
conditions precedent shall have been satisfied or waived by Agent:

(a) Amendment. Agent shall have received this
Amendment fully executed in a sufficient number of counterparts for distribution to all parties.

(b) Amendment to Domestic
Credit Agreement. Agent shall have received an amendment to the Domestic Credit Agreement, in form and substance satisfactory to Agent, fully executed by Borrower and Parent (the Domestic Amendment).

(c) Amendment to Fee Letter. Agent shall have received an amendment to the Fee Letter, in form and substance satisfactory to
Agent, fully executed by Borrower.

(d) EXIM Bank. Agent shall have received the approval of the EXIM Bank, in form and
substance reasonably satisfactory to Agent, for the transactions evidenced by this Amendment and the Domestic Amendment.

(e)
Amended and Restated Notes. Agent shall have received amended and restated promissory notes, in form and substance reasonably satisfactory to Agent, executed by Borrower.

(f) Representations and Warranties. The representations and warranties set forth herein and in the Credit Agreement (other than
any such representations or warranties that, by their terms, are specifically made as of a date other than the date hereof) must be true and correct in all material respects (except that such materiality qualifier shall not be applicable to



---

any representations and warranties that already are qualified or modified by materiality in the text thereof).

(g) Other Required Documentation. Agent shall have received all other documents and legal matters in connection with the transactions contemplated by this Amendment and such documents shall have
been delivered or executed or recorded and shall be in form and substance reasonably satisfactory to Agent.

3.
Representations and Warranties. Each of Borrower and Parent represents and warrants to the Agent and the Lenders as follows:

(a) Authority. Each of Borrower and Parent has the requisite corporate power and authority to execute and deliver this Amendment, and to perform its obligations hereunder and under the Loan
Documents (as amended or modified hereby) to which it is a party. The execution, delivery and performance by each of Borrower and Parent of this Amendment have been duly approved by all necessary corporate action, have received all necessary
governmental approval, if any, and do not contravene any law or any contractual restriction binding on any Borrower or Parent. No other corporate proceedings are necessary to consummate such transactions.

(b) Enforceability. This Amendment has been duly executed and delivered by each of Borrower and Parent. This Amendment and each
Loan Document (as amended or modified hereby) is the legal, valid and binding obligation of each of Borrower and Parent, enforceable against each of Borrower and Parent in accordance with its terms (subject to applicable bankruptcy, insolvency,
reorganization, moratorium or other similar laws affecting creditors rights generally), and is in full force and effect.

(c) Representations and Warranties. The representations and warranties contained in each Loan Document (other than any such
representations or warranties that, by their terms, are specifically made as of a date other than the date hereof) are true and correct in all material respects (except that such materiality qualifier shall not be applicable to any representations
and warranties that already are qualified or modified by materiality in the text thereof) on and as of the date hereof as though made on and as of the date hereof.

(d) No Default. No event has occurred and is continuing that constitutes a Default or Event of Default.

4. Choice of Law. The validity of this Amendment, the construction, interpretation, and enforcement hereof, and the rights of the parties hereto with respect to all matters arising hereunder or
related hereto shall be determined under, governed by, and construed in accordance with the laws of the State of New York.

5.
Counterparts. This Amendment may be executed in any number of counterparts and by different parties and separate counterparts, each of which when so executed and delivered, shall be deemed an original, and all of which, when taken together,
shall constitute one and the same instrument. Delivery of an executed counterpart of a signature page to this Amendment by telefacsimile shall be effective as delivery of a manually executed counterpart of this Amendment.



---

6. Reference to and Effect on the Loan Documents.

(a) Upon and after the effectiveness of this Amendment, each reference in the Credit Agreement to this Agreement,
hereunder, hereof or words of like import referring to the Credit Agreement, and each reference in the other Loan Documents to the Credit Agreement, thereof or words of like import referring to the
Credit Agreement, shall mean and be a reference to the Credit Agreement as modified and amended hereby.

(b) Except as
specifically set forth in this Amendment, the Credit Agreement and all other Loan Documents, are and shall continue to be in full force and effect and are hereby in all respects ratified and confirmed and shall constitute the legal, valid, binding
and enforceable obligations of each of Borrower and Parent to Agent and Lenders without defense, offset, claim or contribution.

(c) The execution, delivery and effectiveness of this Amendment shall not, except as expressly provided herein, operate as a waiver of
any right, power or remedy of Agent or any Lender under any of the Loan Documents, nor constitute a waiver of any provision of any of the Loan Documents.

7. Ratification. Each of Borrower and Parent hereby ratify and confirm in all respects the Credit Agreement, as amended hereby, and the Loan Documents effective as of the date hereof.

8. Estoppel. To induce Agent and Lenders to enter into this Amendment and to induce Agent and Lenders to continue to make advances
to Borrower under the Credit Agreement, each of Borrower and Parent hereby acknowledges and agrees that, after giving effect to this Amendment, as of the date hereof, there exists no Default or Event of Default and no right of offset, defense,
counterclaim or objection in favor of either of Borrower or Parent as against Agent or any Lender with respect to the Obligations.

9. Integration. This Amendment, together with the other Loan Documents, incorporates all negotiations of the parties hereto with respect to the subject matter hereof and is the final expression and
agreement of the parties hereto with respect to the subject matter hereof.

10. Severability. In case any provision in
this Amendment shall be invalid, illegal or unenforceable, such provision shall be severable from the remainder of this Amendment and the validity, legality and enforceability of the remaining provisions shall not in any way be affected or impaired
thereby.

11. Submission of Amendment. The submission of this Amendment to the parties or their agents or attorneys for
review or signature does not constitute a commitment by Agent or any Lender to waive any of their respective rights and remedies under the Loan Documents, and this Amendment shall have no binding force or effect until all of the conditions to the
effectiveness of this Amendment have been satisfied as set forth herein.

[Remainder of Page Left Intentionally Blank]



---

IN WITNESS WHEREOF, the parties have entered into this Amendment as of the date first above written.



STANADYNE INTERMEDIATE HOLDING CORP., a Delaware corporationBy:

/s/ Stephen S. LanginName:

Stephen S. LanginTitle:

Vice President, Chief Financial Officer and SecretarySTANADYNE CORPORATION, a Delaware corporationBy:

/s/ Stephen S. LanginName:

Stephen S. LanginTitle:

Vice President, Chief Financial Officer and SecretaryWELLS FARGO CAPITAL FINANCE, LLC, a Delaware limited liability company, as Agent and as a LenderBy:

/s/ Jason P. ShanahanName:

Jason P. ShanahanTitle:

Vice President




---

Schedule C-1

Commitments



|                                 |  |                     |            |  |             |   |            | 
|-------------------------------- |  | ------------------- | ---------- |  | ----------- | - | ---------- | 
|Lender                           |  | RevolverCommitment1 |            |  | Commitment2 |  
|Wells Fargo Capital Finance, LLC |  | $                   | 10,000,000 |  |             | $ | 10,000,000 | 
|All Lenders                      |  | $                   | 10,000,000 |  |             | $ | 10,000,000 | 



|1 | Notwithstanding the following, (A) the aggregate amount of the Revolver Commitments of the Lenders hereunder, as of any date of determination,
shall not exceed the lesser of (i) the Maximum Revolver Amount as of any date and (ii) the Borrowing Base as of any date, and the Revolver Commitment of each Lender hereunder shall be deemed to be temporarily reduced proportionate to such
Lenders Pro Rata Share to the extent either the Maximum Revolver Amount or the Borrowing Base is less than the aggregate amount of the Revolver Commitments, and (B) the aggregate amount of the Revolver Commitments under this Agreement
combined with the aggregate amount of Revolver Commitments (as such term is used in the Domestic Credit Agreement) shall not exceed $30,000,000.
|- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



|2 | Notwithstanding the following, (A) the aggregate amount of the Commitments of the Lenders hereunder, as of any date of determination, shall not
exceed the lesser of (i) the Maximum Revolver Amount as of such date and (ii) the Borrowing Base as of such date, and the Commitment of each Lender hereunder shall be deemed to be temporarily reduced proportionate to such Lenders Pro
Rata Share to the extent either the Maximum Revolver Amount or the Borrowing Base is less than the aggregate amount of the Commitments, and (B) the aggregate amount of the Commitments under this Agreement combined with the aggregate amount
Commitments (as defined in the Domestic Credit Agreement) shall not exceed $30,000,000.
|- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------