Fuel pressure gauge: What size connection?

[jlex]

I sometimes have a hot start problem on my '85 Carrera; takes a bit more cranking after letting it sit sometimes. My guess its either a bad check valve on the fuel pump or a leaking injector. Anyway, I wanted to start out by checking the active & residual fuel pressure at the rail.
Ordered an inexpensive fuel pressure gauge over the internet that seemed to have lots of fittings, but the closest one was a bit too loose. Looks like I need to scout out a female fitting to go over the test port on the fuel rail that I can tie into a hose...
Does anyone know what size the thread is on the fuel test port? I suppose it's metric w/ a certain pitch... Tried an auto supply store & a plumbing supply today w/o any luck. Advice is appreciated.

regards,

Jlex.

[jlex]

If no one knows the correct size so I can retrofit my tester, do you have any recommendations as to where to purchase an inexpensive one that fits? Thanks.

jlex.

[jlex]

One last try w/ this post...
If no one knows the fuel port test size, then does anyone have a recommendation as to where I can buy an inexpensive fuel pressure tester that'll fit the 3.2? Thanks.

jlex

[hobieboy]

Going from memory, its M14. What I did to be sure is bring the female cap to a hydraulic shop; not auto supply

[jlex]

Hey, hadn't thought of that; would surely have something at a shop that works on hydraulics. Appreciate the reply Hobieboy

[Peter Kelly]

It is a metric inverse flare. It is next to impossible to find an adapter for it to go to AN. Try Baum tool, I think they have a fuel pressure tester.

[jlex]

Thanks, Peter; Looks like Baum tools doesn't post much info on their web site; they want to send a hard copy catalog. Looks pretty pricey for a one-time use tool.
If anyone out there has a replaced fuel line (the connectors look the same size as the test port) with the connector still attached, I should be able to cobble a connection between my gauge & the test port... please let me know.

regards,
jlex.

[lally911]

I took the cap off the test port on my 84 and a m12x1.5 bolt screws in to it.

[jlex]

Thanks for taking the trouble to check it out for me Keith. There's another thread on here that started a couple of days ago asking where a pressure gauge that fits could be located, and one of the replies from a guy who made his own adapter said, like you, 12X1.5MM is the size. That confirms it for me. Either I'll get a tap & make a connector OR IF SOMEONE OUT THERE HAS A DISCARDED LENGTH OF FUEL LINE WITH THE CONNECTOR ON THE END, LET ME KNOW & I'LL RIG IT TO MY TESTER.

regard,

jlex.

[cgarr]

jlex, if you want I can make up another fitting, all you would need is to get a 1/8 pipe barbed end to fit your tester hose, PM me your address and I can send you one out.

[jlex]

Craig: Wow, that would be terrific... I'll PM you right away.
(This is a link to the other thread I mentioned showing Craig's adapter in a picture 3.2 fuel pressure tester?)
That'll certainly save me the cost of buying the tap & locating a blank to make the adapter from. Am glad to pay for your time & trouble, Craig. What a great forum!

regards,
jlex.

[euro911sc]

I have been thinking about doing the same thing, except on a CIS setup. Any reconmendations on how/where to put in a fuel pressure gage in the engine compartment? I have seen several, but they were all done on carb setups...

Best regards,

Michael

[jlex]

Michael: can't answer your question, but do a search on it. I remember reading a thread on members who did a gauge installation. Their primary concern was possible leakage into the closed engine compartment....

Cgarr made good on the promise of an adapter.... good man! This weekend, I hooked it up after buying a barbed connector for my hose end & it worked just fine. Readings showed a few pounds pressure above normal w/ doing a jumpered test and with engine running. Fuel regulator disconnect test per Bentley was pretty close also.

Residual pressure test was a stinker, though. Instead of maintaining about 15lb pressure 20 min. after shutdown, it went to 0 in about 5 minutes. Without a shot of gas as in a cold start situation, hard start due to the lack of pressure is the result.

Question is whether the pressure drop is due to a faulty check valve on the fuel pump, or one or more leaking injectors? Bentley says pinch one of the fuel return lines to rule out the check valve... impossible. Those gas lines are too thick & are covered w/ spiral wire to eliminate kinking.
Because once I get it started & put on the gas it dies, then goes okay after getting the car rolling, my guess is it's flooded which means leaking fuel injector(s).
Pulled the injectors yesterday & sent them away for testing & cleaning. Am asking the company to check for leaking on the pre-cleaning test. Will post again in a couple of weeks after reinstallation & checking to let everyone know...
As a side note, getting those injectors out isn't the walk in the park I expected. Had to disconnect each rail in one spot; would have liked to disconnect the left rail at the pressure regulator, but another hose right on top of the connector kept me from getting a wrench on it... hopefully the injector will go back in okay.

Thanks again to cgarr for the assist...

regards,

jlex.

[jlex]

Just a short note to close out this thread.
I pulled the injectors & sent them for cleaning. After reinstalling them, I checked the residual pressure again & this time it held at about 15lb. Prior to cleaning, residual pressure dropped to 0 after only 5 minutes.
This is probably the cause of my difficult hot start problem (flooding from leaking injector(s).

Thanks again to cgarr for the time & trouble in making the connector for my pressure tester.

regards,

jlex.

[aston@ultrasw.c]

I happened to find a suitable fitting off the shelf!!

I am installing a fuel pressure gauge, so I wanted something reliable rather than a quick test set up.

Here it is:

http://www.hydraulic-supply.com/pdf/1121.pdf

It works great, no leaks.

[Talewinds]

Originally Posted by aston@ultrasw.c

I happened to find a suitable fitting off the shelf!!

I am installing a fuel pressure gauge, so I wanted something reliable rather than a quick test set up.

Here it is:

http://www.hydraulic-supply.com/pdf/1121.pdf

It works great, no leaks.

Cool so which fitting did you buy? And where did you install it? In place of that access cap towards the back of the driver's side fuel rail?

[aston@ultrasw.c]

C1AK70 M12x1.5, other side is 4-AN

Summit Racing has a huge selection of AN fittings.

DS fuel rail. Just lubricate the threads, no sealant required.

[jlex]

Yikes; $29 for the adapter including shipping...
Must be 12k gold plated.

jlex.

[getluky]

Nice, i'm keeping this thread saved for the next time I need to debug my fuel injectors.

[aston@ultrasw.c]

FYI, These guys did a super job cleaning out my injectors.

http://www.rceng.com/Fuel-Injector-Cleaning-P43C0.aspx

I thought they had messed them up and replaced with new!!