Fuel Check Valve on fuel line in engine bay?

[7783911]

I occasionally get a hot start issue and am thinking it could be the check valve..but honestly don't want to open a can of worms by redoing the fuel pump and possible issue with banjo sizes etc. I did already replace the accumulator with a later model larger one (tested beforehand).

SO

Has anyone installed a check valve in their engine bay and if so, on the fuel line in or the return line?

was thinking something simple like this

https://www.amazon.ca/uxcell-Non-Return-Aluminum-Stainless-Adjustable/dp/B0916398G4/ref=sr_1_6?crid=3B8QSJODSSBRB&keywords=7mm+od+fuel+check&qid=1679261134&sprefix=7mm+od+fuel+check%2Caps%2C112&sr=8-6

This matches the 7mm ID of a fuel hose

Len..anything special you've made up in the past/present?

Thanks

Bob

[PeteKz]

Check valve must go between the fuel pump and the accumulator. Check your accumulator first to be sure it's good by unscrewing the return line from the accumulator, then running the pump (and plug the return line that you removed or you will get fuel out of it). Then run the fuel pump. If you get any gas out of the bottom of the accumulator, it's bad. If you do not get fuel out of the bottom of the accumulator, then you need to to a pressure test and check how long the system holds pressure.

[7783911]

Tx Pete

Yes, a pressure test was done a couple of years ago, I will repeat. If I put a check valve in the engine bay as you say on the accumulator...it should be on which line (of 3)?

[BoxsterGT]

7783911 -

You do not identify the model year but certainly a CIS fuel system.

CIS runs on high fuel pressures, and should not have hose clamps on the Pump (pressure) side of the fuel system.

Only CIS model years using hose clamps were 73.5 and 74, and after that Porsche went to crimped fuel connections.

Just a word to the wise. Fuel leaks and fires are a big NO NO.

Len

[7783911]

Thanks Len

its a 77 with a 83 3.0 transplant

I guess I have to risk going into the pump to see what size banjo is there, i dont want to replace the fuel lines if I dont have to..I know there was a post on adapting to different size banjo's so may have to look into that if indeed my pump has an external CV. If Internal and pressure testing shows a problem, then I need to replace the pump which as you know is limited to Mexican Bosch units that frankly dont impress many folks for their workmanship.

[BoxsterGT]

You can easily tell what size banjo you have by the wrench size of the end cap.

A 10mm Banjo has a 17mm cap, a 12mm Banjo has a 19 mm cap.

Len

[Damon88]

In the same situation. My fuel pump with internal check valve needs replacement. I already replaced my fuel lines with new 10ml from Len. Anyone have a solution or a proper part # for the fuel pump I need for my 78 911sc. I have confirmed after pressure tests and diagnosis that it is indeed my check valve in fuel pump. Cheers.

[BoxsterGT]

Damon88-

Show us the pump. If like this one.....



....a check valve is available for about $20 from out host if I remember correctly.

Len

[Damon88]

Thanks for replying Len. Here is a picture of the style of pump in my car. found it of an old thread.

[BoxsterGT]

Here is the check valve offered by our host:

https://www.pelicanparts.com/More_Info/0000900110.htm?pn=000-090-01-10-M14&bc=c&SVSVSI=

$25 plus shipping. Please verify application with Pelican Parts before purchase.

Len

[Damon88]

Originally Posted by BoxsterGT

Here is the check valve offered by our host:

https://www.pelicanparts.com/More_Info/0000900110.htm?pn=000-090-01-10-M14&bc=c&SVSVSI=

$25 plus shipping. Please verify application with Pelican Parts before purchase.

Len

Thank you Len. I can seem to find any info to confirm if this is a 10mm or 12 mm. My current fuel lines are 10mm. cheers

[BoxsterGT]

This is 12mm. Hose size is not Banjo size.

I miss-spoke earlier. Measure the Banjo OD with a wrench, not the Cap Nut.

I would be surprised if a 78SC still used 10's.

Once known, ask Pelican sales for the correct one. They are very helpful and will find one for you.

I have both if needed, but first ask our host.

Len

[Damon88]

Ok makes sense. thank you for the help Len. Much appreciated. Cheers

[BoxsterGT]

I found the two different Banjos, 10mm and 12mm in my stock.....



and placed open wrenches next to them. The 10mm Banjo has a 17mm OD (on Right), the 12mm Banjo has a 19.8mm OD (on the Left).

This is the easiest way of determining the Check Valve size. A 17mm wrench slips over the 10mm Banjo. The 19mm wrench does not quite fit over the 12mm Banjo OD.

Whatever Pump & Check Valve you have, a replacement Feed hose to the Accumulator can be made up when needed.

If buying new Fuel lines AND new Pump, I strongly recommend going to the 12mm size. The early version 10mm Pumps are getting harder to find AND more costly. The later 12mm size are used everywhere, so more are made and easier to find and cheaper as well.

Hope this helps end the confusion. Even the Porsche dealers do not always know the differences.

Len