[gke60]

thanks to those who replied to MY issue, i think things are going a bit off the original post, and getting personal.
i did not intend this, just after a little help to something i was having a problem with.
cheers

[Boostedbird]

Originally Posted by gke60

thanks to those who replied to MY issue, i think things are going a bit off the original post, and getting personal.
i did not intend this, just after a little help to something i was having a problem with.
cheers

Fair enough. I should have sent a pm if I wanted to say something to someone else. Sorry to cloud your post. Seemed like people were condemning the pumps saying that they all had low pressure from day one when in actuality their problem seems like a false gauge reading as discussed. I was pretty much discussing your issue.

[68WarDog]

Continuous steady speed with that combo and NO return line, vapor lock, gets my vote. Had past combo with very similar setup. No problem at dragstrips

[gke60]

Originally Posted by Boostedbird

Fair enough. I should have sent a pm if I wanted to say something to someone else. Sorry to cloud your post. Seemed like people were condemning the pumps saying that they all had low pressure from day one when in actuality their problem seems like a false gauge reading as discussed. I was pretty much discussing your issue.

cool no worries, just trying to sort out a problem.
cheers

[FrankieT/A]

Originally Posted by Lee

You need a return-line regulator. You are probably (like most of us) being forced to run gas with ethanol in it. That crap vapor locks.

I was on the Hot Rod Power Tour a few years ago, with outside temps in the 100's for most of it, and there were cars on the side of the road with vapor-locked fuel systems every day.

Insulate the fuel lines near any exhaust pipes, and install a return line.

I have a return line, 5/16 with the RobbMc special fitting...

[FrankieT/A]

78W72,
My combo is not that radical mildly ported 6X-4's, Ram Air IV cam, RA IV intake and RA III ex manifolds. Certainly not 500 HP. If the 550 pump can't handle that then they shouldn't even bother with the 550 and just sell the 1100.

[HoneyHush]

It's late and I've been thinking about your problem so ill offer a few observations that may help. 1-the fuel guage will not show pressure when the engine is off, it's not fuel injected....if it had pressure it would push fuel past the needle and seat and flood the engine. 2- the guage shows pressure when the engine is running....I believe the pump is good. 3-the fact that you can pump the pedal and restart the car after it has died tells me there is fuel in the carb....another indication that the pump is good. Wouldn't have any fuel in there if it ran out of fuel from a bad pump. 4- don't believe a vapor lock situation because the car starts right back up. 5- the fact that it happens at such a low rpm and the symptons you describe would point me to check a low voltage situation (not powering the msd box properly), or a bad ground somehow. The system has been working properly for 4 years, I don't see the need to totally redesign the system or start over. I've been running a dead head system for 10 years with no problems. It is probably the most popular arrangement there is. I believe the problem is in the alternator or msd system. Just my opinion based on the facts you stated

[gke60]

Originally Posted by HoneyHush

It's late and I've been thinking about your problem so ill offer a few observations that may help. 1-the fuel guage will not show pressure when the engine is off, it's not fuel injected....if it had pressure it would push fuel past the needle and seat and flood the engine. 2- the guage shows pressure when the engine is running....I believe the pump is good. 3-the fact that you can pump the pedal and restart the car after it has died tells me there is fuel in the carb....another indication that the pump is good. Wouldn't have any fuel in there if it ran out of fuel from a bad pump. 4- don't believe a vapor lock situation because the car starts right back up. 5- the fact that it happens at such a low rpm and the symptons you describe would point me to check a low voltage situation (not powering the msd box properly), or a bad ground somehow. The system has been working properly for 4 years, I don't see the need to totally redesign the system or start over. I've been running a dead head system for 10 years with no problems. It is probably the most popular arrangement there is. I believe the problem is in the alternator or msd system. Just my opinion based on the facts you stated

thanks for the ideas, i thought electrical at first to, i have conducted all of the tests as per the msd troubleshooting guide for dizzy, coil & 6al2 box, even put a new cap & rotor in as the carbon pip had vanished from the cap, still not saying its not the msd though.
alternator appears ok still charging ok, still not saying its not this either , just appears ok, this is why we have moved to the fuel system.
in the past when the car is shut off it still had fuel pressure for quite some time after, now it drops to 0 in 30 mins, weird.
my mechanic thinks the diaphragm in the fuel pump may have a small hole in it as the problem only happens when up to operating temp, seems fine when cold, so pump heats up hole gets bigger.
i thought an o ring may have gone bad in the regulator, i am not a mechanic, lol.
cheers & thanks, i will keep at it.

[HoneyHush]

Had a friend go through a very similar problem with his boat. It would run and shut off start right back up run shut off it turns out that it was a bad coil. He also went through two fuel pumps before he found the problem. When they heat up they go bad. I hope this helps your problem

[78w72]

Originally Posted by FrankieT/A

78W72,
My combo is not that radical mildly ported 6X-4's, Ram Air IV cam, RA IV intake and RA III ex manifolds. Certainly not 500 HP. If the 550 pump can't handle that then they shouldn't even bother with the 550 and just sell the 1100.

i undestand, but again, the problems happen under hard acceleration, if you have decent traction you are fighting pulling fuel through all that line under g-force... the HP rating of the pump is for when its standing still & very short line to feed it. most engine dynos have like a 2-3ft fuel line directly into a tank or can. edelbrock claims their pump is good to 600hp... couldnt support 500 in real street/track use & actually probably went lean on teh dyno & hurt the final numbers. wish i could dyno the engine again with the new pump.

i agree the 550 should support your combo but in real world driving you cant rely on those numbers. i have read others useing the 550 had no problems into the low 12's with it. i almost bought the 550 for my car since it only made 520hp... but after talking with robb & reading the fine print on the pump, the concensus was it wouldnt be enough under hard acceleration.

gke60: i have heard of ignition modules being bad or intermittent in msd distributors & even GM ones. when they start to go bad heat can make them act up. good luck tracking it down.

[gke60]

gke60: i have heard of ignition modules being bad or intermittent in msd distributors & even GM ones. when they start to go bad heat can make them act up. good luck tracking it down.

thank you, still working on it, been through the whole fuel system, start up tomorrow.
its an msd pro billet so no module in the dizzy, have checked magnetic pick up and checked fine, i will replace it if the fuel system checks ok.

[FrankieT/A]

Originally Posted by 78w72

i undestand, but again, the problems happen under hard acceleration, if you have decent traction you are fighting pulling fuel through all that line under g-force... the HP rating of the pump is for when its standing still & very short line to feed it. most engine dynos have like a 2-3ft fuel line directly into a tank or can. edelbrock claims their pump is good to 600hp... couldnt support 500 in real street/track use & actually probably went lean on teh dyno & hurt the final numbers. wish i could dyno the engine again with the new pump.

i agree the 550 should support your combo but in real world driving you cant rely on those numbers. i have read others useing the 550 had no problems into the low 12's with it. i almost bought the 550 for my car since it only made 520hp... but after talking with robb & reading the fine print on the pump, the concensus was it wouldnt be enough under hard acceleration.

gke60: i have heard of ignition modules being bad or intermittent in msd distributors & even GM ones. when they start to go bad heat can make them act up. good luck tracking it down.

I understand what your saying but we're not talking hole shot from standing start...we're talking getting to an entrance ramp and accelerating hard through second and third.

[ta man]

Originally Posted by FrankieT/A

I understand what your saying but we're not talking hole shot from standing start...we're talking getting to an entrance ramp and accelerating hard through second and third.

Lots of G's on the ramps here too..at the dragstrip or on the street..many times it will be the top of 2nd or 3rd gear the fuel pressure will fall off.Anyone suspecting any fuel pressure issues should have a fuel pressure gauge hooked up to monitor pressure..its an eye opener!

[lust4speed]

Let's focus on gke60's problem. Two things really stand out: the engine starts right back up, and the problem occurs at just about the lowest possible demand time with RPM very low along with mild throttle position. Most problems I can think of involving fuel would also continue and screw up the restart.

Only thing I can come up with (and not that good of fit) is a partially clogged vent on the tank which would starve out the pump - and then given a few moments to reduce the vacuum in the tank, fuel could be pulled again. While possibly a little fuel would always be pulled, it wouldn't be enough to support cruise RPM, but given a bit to recover would possibly support idle RPM.

gke60, what happens when you floor it from a stop and go up through the gears? Don't think we've covered that yet.

[gke60]

sorry to have not updated this, been away.
we finally sorted it out, even though we missed race day.

issue of fuel pressure was a faulty gauge also fuel tank had a dent in it that left the pick up close to tank bottom, it may have been dented at the paint shop, not sure.

the cutting out problem was actually the msd, hvc, 8252 coil, it was throwing us off because it checked ok with the tests msd say to perform and it started straight away after it had cut out, this is the second one of these I have had go bad in the last few years, the first one just totally failed and checked out dead with the tests.

the car is back running as good as ever, with my new detriot trutrak, strange case and 3.55 highway gears it ran 11.18 @ 123 mph.

thanks for every ones input.

[78w72]

good ol msd! glad to hear you got it sorted out... & the robbmc pump was not the problem & the gauge was not correct after all...

thats why i went with a GM hei tweaked by suntuned... from what ive read there is no power in an msd dist or their boxes & coils, at least not at this level, just potential problems waiting to happen.

gke60: whats your car weigh? those are some great 1/4 mile times from your combo.

[gke60]

sorry it has not been weighed, something I have to get around to.
its a full weight street car, ( not daily driven ) with sub frame connectors.