Losing fuel pressure after running for a while

[FuzzyBug]

I have a Carter rotary electric fuel pump that has been working fine for quite some time on 1776 with dual 40 weber idfs in FG dune buggy. Pump is located on front wall by tank. Never verified pressure, but it ran fine. I recently installed a new 2110 engine with dual 44 IDF and decided to install a fuel pressure gauge this time to verify fuel pressure. The fuel line Tee's at the back of the fan housing feeding to both carbs and to the gauge which is mounted to the upper left side of the fan.
When I turn on the key and pressurize the system, it reads around 2.5 - 3 PSI on the gauge. Starting the engine, it stays at the same pressure. However, after running for awhile, the gauge drops to zero, but the car still runs and doesn't seem to be impacted by the low/zero pressure. They pump continues to run and appears to be providing gas. Can't find any leaks and car is not flooding out or appear to be dumping fuel into carbs
1) Anyone else ever have this issue?
2) Bad pump?
3) Vapor lock on gauge? I wouldn't think it's too hot being in open air, but maybe since it's on fan housing ?
4) Bad gauge? -reads ok when starting up
5) clogged filter before pump? - How often do these need to be changed? Are they independent or part of the pump

I have loosened the gauge while running thinking it may have an air bubble behind the gauge, but it squirts out gas when loosened.

Any input would help. Thanks

[FuzzyBug]

Any comments? Anyone?

[vwracerdave]

Yes the gauge could be going bad.
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[jason]

Does it build pressure back up at idle? If it does your carbs are sucking more than it can supply. Could be a bad pump.

[buggnuttz]

Throw away guage. If it seems to run good with no flooding its good to go
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[jason]

Turn it off when it reads zero next time. Turn key on without starting. If it builds pressure, there's your answer.

[FuzzyBug]

It does not build up pressure at idle, and once the gauge is at zero, it doesn't raise back up until its started from cold start again. (sitting over night as example). Turning off engine and then restarting or letting the fuel pump run before starting does not raise the gauge, only when it has cooled back down. Car seems to run fine, though. Any recommendations on a good replacement gauge?

[vwracerdave]

If it runs and drives fine when the gauge is reading zero than it is not the pump. If the pump was bad it would not run. A Carter rotary pump should be plenty big enough to supply a 2110.
_________________
2017 Street Comp Champion - Thunder Valley Raceway Park - Noble, OK
2010 Sportsman ET Champion - Mid-America Dragway - Arkansas City, KS
1997 Sportsman ET Champion - Thunder Valley Raceway Park - Noble ,OK
Featured in Dec. 2001 HOT VW's Magazine page 63

Watch my racing video's http://www.youtube.com/user/okvwracer/videos

[rs58rag]

Is your gauge liquid filled?

[modok]

Yeah, leaky gauge.

What brand? not sure
Do you want a accurate gauge to check fuel pressure, like a mechanic's tool?
Or one permanently mounted to the car to waste money and increase fire hazard?

[FuzzyBug]

Gauge is liquid filled and from Summit Racing. I was using gauge to check pressure and assumed I could leave it on the car. I am not seeing any leaks anywhere so If gauge is leaking, it must be internal? Not looking to waste money, but I had the gauge and wanted to know the pressure to be sure I had proper fuel pressure to the carbs. It was one of the things on the list to tuning the carbs (ensure proper pressure)

[modok]

You didn't really answer the question.

If you need a gauge that can be put on the car and withstand vibration, it needs to be pretty stout to hold up, so it's probably going to cost 50$ minimum. But does a "peoples car" have gauges all over it? I don't think so, that's some rich peoples game. I think the mechanic should have the pressure gauge and the driver should drive, so personally I'd go with the mechanic's combo vac and low pressure gauge.

Buy both. there you go, It's your money I'll spend it as I see fit

Even better, is throw the gauge away and buy nothing. For 60$.....you buy a spare fuel pump.....one that actually puts out the pressure it's supposed to, so you don't even need a gauge!

[earthquake]

How is your tank vented? loosen the cap and see if it does the same thing just don't hot rod it and slosh fuel every where.

Casey
_________________
74 CLASS 11 LOOK-A-LIKE
69 DUNE BUGGY
79 INTERNATIONAL SCOUT II
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98 Ford E150
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[74 Thing]

It is your liquid filled gauge. On the back there is a rubber plug-when it heats up it gives incorrect readings-take out the plug to burb it when it reads incorrectly then replace it or better yet remove the gauge from the engine compartment and just tee in a vac/pressure gauge for testing purposes then remove it when you are done.

[Slow 1200]

throw the gauge away, problem solved

[old gh bug]

Did you resolve the problem you were having , as i am running exactly the same 2110 twin 44 idfs and i am having the same problem with my gauge but its not liquid filled? im going to investigate more this weekend , i think i may have a partial blockage or some restriction as my car starts to stumble a mile or so down the road due to the lack of fuel i think ??

[Dale M.]

So if you are not running out of fuel while performance driving (WOT) why do you need gauge... You can't see when you are driving if its in engine compartment...

Dale
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All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ...

[mreid55]

Wondering if you ever figured out what was going on with your pressure? I just installed a new cater style 3.25 rotary and new cheap non-liquid filled gauge (installed in proper location on a 550 spyder under tank). Started off dead nuts at 3.25. After warming up, it approached zero. Concerned I had a cheap gauge, I purchased a liquid filled from Summit. Same thing. Pulled pump and drained to look for any junk (even thought I knew the tank was squeaky clean. No junk so thought perhaps new pump had gone bad or I clamped it to tight to front axle and distorted housing. Bought another new pump and installed. Same thing. Dead nuts on when cold. Drove the car around for a while and at zero when I returned. Woke up this morning, fired it up. 3.25 but as it started to warm, the pressure on gauge started to drop again. No indication of any flooding. I'm going to take it out for nice long spirited drive and If it has no problems, I'm going to quit worrying about it (ignorance is bliss) but don't like unsolved mysteries so just wondering if you figured it out

[FuzzyBug]

Unfortunately, I did not figure it out and it still bothers me. However, I ended up taking off the gauge and putting a plug in its place incase I need to check pressure again. Not really sure why it operates like that, and with several gauges, too. You have the exact situation I had, but I gave up.

[HBRag]

Liquid filled gauges will loose 6-7 lbs of indicated pressure as they heat. Been there, done that with a Summit gauge even...