several years ago, i had the bowls off to fix some leaks...actually, i need to do that again. Don't recall making any float adjustments however. How might the need to increase the idle play into this, if at all? thanx for

I can't think of any possible scenario where something wrong inside your carburetor could cause the the fuel pressure to be 9 psi from a mechanical pump. And the fact that the electric pump comes on with a 2 to 3 psi, and then levels off at 6 psi, would indicate that the pressure gauge is probably OK.

You know, the simplest, easiest, quickest, and least expensive test would be to just pull the two lines off your mechanical fuel pump and temporarily plug them together, fire her up, check the pressure on the gauge, and take her for a nice romp and see how she runs.

all i need is time (away from work!). i'll keep you posted. s

OK, i skipped school part of the morning and went out to the garage. At start up, the pressures were normal (3 PSI w/o the e-pump and then 6 with the e-pump). On the road, they were as they had been before the 9PSI fiasco....no more elevated pressures....all as it had been in the years before. Drove the car to work...steady 6 PSI with the e-pump, tho', as before, dropping to 3 PSI under load without it. Interestingly, when I shut the car off, the gauge read 8 PSI. Since I don't seem to have the problem I had on Sunday (going to 9 PSI), I"ll con't to drive the car and see how it goes. Seems like a bad idea to remove the mechanical pump for no good reason...might save my butt if the e-pump ever failed. Any other thoughts? thanx steve

How is your gauge plumbed in to your fuel system? Meaning, is it all mechanical and you have an actual fuel line running to your dash gauge, or is there a pressure sensor there on the engine, either mechanical or electrical, etc. It can make a big difference because of the heat. For instance, my liquid filled pressure gauge, sitting about six inches away from the carb inlet, registers zero psi when the underhood temperature gets hot. Almost all do, unless they have a pressure release mechanism.

All mechanical...at the end of the fuel log/rail there's liquid filled line that goes to the gauge.
(autometer). sa

Do you feel like buying a new $100 mechanical fuel pump and just rolling the dice to see if the new pump makes everything better (without the need to turn on your electric pump)? I think that's probably what I would do. I just don't like leaving a part on the car that is not up to snuff. I don't know if it could actually leak much (either externally or internally) -- I drove a car for two years decades ago that dripped a drop of gas out of the fuel pump diaphragm every five or six seconds and nothing ever happened, other than poor gas mileage. %/

When all's said and done, it would cost about $100 to buy the blocking plate and find the right aeroquip or equivalent way to connect the two fuel lines. What pump would you buy? Might even be easier, in some ways, to replace the mechanical pump than to figure out the re-plumb. thanx steve

When I threw out a hundred bucks, I was thinking of this tried and true pump: https://www.summitracing.com/parts/CRT-M6905/ But, others might have other suggestions. And you should also expect somebody to complain about you having a fuel line running in to the dash without an isolator. I've never touched an isolator, so I won't comment on it.

Thanx for the link. I have an isolator between the fuel log and the gauge. I'd be afeared to run gasoline into the cockpit...hate for my cigar to light it up. s

Got out to the car this PM and despite kicking on the e-pump the pressure never got to be more than 3-4 PSI, the car started but died about 100' later. Couldn't restart and pressure remained at 3 with or without the e-pump. Cranked OK, but would never fire. I needed to get home, so my wife took me, leaving the car parked at work. Tomorrow I'll see if I have spark or fuel or whatever I can determine. Could the mechanical pump fail in such away that the e-pump can't bring fuel to the rail? Or, is this just another problem before I start cussing, swearing and throwing dangerous objects? thanx s

Steve - what type of fuel tank do you have? Is it one of those bladder style tanks or a fuel cell with foam? Kind of sounds like something restricting flow from the tank.

Well look on the bright side. A no-start/no-run condition is a heckuva lot easier to figure out than an intermittent, car still runs, but misbehaves condition. Even if the car starts, I would not drive her home -- 1) you could stall on the highway, which is a danger; and 2) there's a small chance that the loss of fuel pressure is the result of "internal bleeding" in to the oil pan. I don't think that's happening, but I'm not going to risk your engine on it. Put her on a flatbed and get 'er home. Then we'll figure it out.

Not a fuel cell. Stock from Kirkham. Thanx for the advice. More later. s

Yeah, just to be on the extra-safe side, check your dipstick to see if the oil level is unusually high, or if it looks funny, or if it smells like gas. Having owned her for 15 years, you know what it normally looks like on the end of the stick.

thanx. BTW, could a failed mechanical pump, ,plumbed the way mine is, cause a low pressure, even tho' the e-pump seems to be working OK? Am I making sense? s

Without it leaking, I'm going to say "No." Here's why: Think of your home's water pressure, which is usually around 80psi. So, if you put a pressure gauge on the end of your garden hose, with the hose not running, it will show 80psi. If you stab a really skinny, hollow swizzle stick in to the side of the hose, and put a gauge on the end of the swizzle stick, it will read 80psi as well. Obviously the flow out of the swizzle stick end would be much less than the flow out of the hose end, but the pressure will be identical throughout, provided there is no flow anywhere. When you turn your electric fuel pump on, and the car is not running, after a few seconds the pressure will be identical throughout the fuel system unless 1) there is a complete clog (in which case the pressure after the clog will be zero); or 2) there is a leak somewhere down the line that is reducing the pressure. In our swizzle stick example, a small crack in the swizzle stick will create a larger pressure drop at the end of the stick than the identical crack would cause in the hose itself, because of the volume of flow is much greater in the bigger hose. So, what this means is that if your electric fuel pump is really putting out, through its regulator, 6psi and the pressure on the far end of your fuel line run, at the fuel pressure gauge, reads 3psi, and the car is not running, then there must be a leak somewhere.

OK, got out to the car at lunch....fuel pouring out the secondary vent tube with pump on...flooding everything within 10 miles. I assume it 's a stuck float and hope to fix it over the weekend. Did have the presence of mind to bring a rubber hammer, but a few wacks on the bowl only made me look an idiot in a parking garage full of fuel injected SUVs. s

That's the leak.:D Curious that it would pick now to give you trouble.... If it was me, I would just go get a plug at the auto parts store and plug off the secondary fuel line feed there going in to the inlet and then drive her home on the primaries (which she runs on 99% of the time anyway). Once you get her safely home then we can figure out what's going on.

You have apparently been having this problem off and on for awhile.

http://www.clubcobra.com/forums/shop...-pressure.html


Did you manage to solve it back then? I think I would question how accurate the gage is but obviously you are having some problems so it's not all in the gage.