An assembly comprising: a first component having a first outer surface and a plurality of spaced extensions (102, 102A) extending outward from the first outer surface; a second component having a flexible rim surrounding a cavity; wherein the rim has spaced recesses; wherein the rim is biased toward an unflexed state when in a flexed state; wherein the first component is configured to fit at least partially into the cavity with the rim flexing to surround the first component and trap the extensions (102, 102A) in the recesses, wherein the extensions (102, 102A) are configured to prevent the rim from returning to the unflexed state over a predetermined range of operating conditions, the bias of the rim thereby forcing the first component toward the second component over the predetermined range of operating conditions; additional components supported by the first component and the second component at least partially in the cavity; and wherein bias of the rim causes the first and second components (23, 12) to force the additional components toward one another; wherein the first component is an end cap; wherein the second component is a vapor valve housing; wherein the additional components include a jet pump nozzle and a nozzle carrier supporting the jet pump nozzle; characterized in that: each extension (102, 102A) has a base with a first width at the outer surface of the first component, each recess has a second width narrower than the first width to prevent the base from fitting within the recess under the predetermined range of operating conditions; each extension (102, 102A) has: a ridge; a first angled surface and a second angled surface each extending from opposite ends of the base and meeting at the ridge; an edge of the second component at the recess in which the extension is trapped rests along the first angled surface under the predetermined range of operating conditions; the first angled surface has a first portion and a second portion; the first portion has a first incline relative to the base; the second portion has a second incline relative to the base; the second incline is steeper than the first incline; and the first portion extends from the base to the second portion, and the second portion extends from the first portion to the ridge a first component having a first outer surface and a plurality of spaced extensions (102, 102A) extending outward from the first outer surface; a second component having a flexible rim surrounding a cavity; wherein the rim has spaced recesses; wherein the rim is biased toward an unflexed state when in a flexed state; wherein the first component is configured to fit at least partially into the cavity with the rim flexing to surround the first component and trap the extensions (102, 102A) in the recesses, wherein the extensions (102, 102A) are configured to prevent the rim from returning to the unflexed state over a predetermined range of operating conditions, the bias of the rim thereby forcing the first component toward the second component over the predetermined range of operating conditions; additional components supported by the first component and the second component at least partially in the cavity; and wherein bias of the rim causes the first and second components (23, 12) to force the additional components toward one another; wherein the first component is an end cap; wherein the second component is a vapor valve housing; wherein the additional components include a jet pump nozzle and a nozzle carrier supporting the jet pump nozzle; each extension (102, 102A) has a base with a first width at the outer surface of the first component, each recess has a second width narrower than the first width to prevent the base from fitting within the recess under the predetermined range of operating conditions; each extension (102, 102A) has: a ridge; a first angled surface and a second angled surface each extending from opposite ends of the base and meeting at the ridge; an edge of the second component at the recess in which the extension is trapped rests along the first angled surface under the predetermined range of operating conditions; the first angled surface has a first portion and a second portion; the first portion has a first incline relative to the base; a ridge; a first angled surface and a second angled surface each extending from opposite ends of the base and meeting at the ridge; an edge of the second component at the recess in which the extension is trapped rests along the first angled surface under the predetermined range of operating conditions; the first angled surface has a first portion and a second portion; the first portion has a first incline relative to the base; the second portion has a second incline relative to the base; the second incline is steeper than the first incline; and the first portion extends from the base to the second portion, and the second portion extends from the first portion to the ridge