New 347 Build... '75 Street Queen

[broncnaz]

Check your gas caps maybe the vent is bad in them and its not allowing air into the tank and your creating a vacuum which keeps the fuel from pumping.

 

[chuzie]

My fuel pressure gauge is one of the single best additions I have made to my rig. Gives me instant troubleshooting feedback and save me tons of time. Get one and stick it on the hood.

 

[Mountain Ram]

Check your gas caps maybe the vent is bad in them and its not allowing air into the tank and your creating a vacuum which keeps the fuel from pumping.

Both caps are less than a year old... I will try it, but not putting a lot of faith there.

My fuel pressure gauge is one of the single best additions I have made to my rig. Gives me instant troubleshooting feedback and save me tons of time. Get one and stick it on the hood.

I have a screw on gauge but fubar'd the seal. Didn't get any spray of gas out of the fuel line valve... What do you mean stick it on the hood?

 

[Mountain Ram]

I get a slight smell of fuel in the vacuum line to the regulator... Is it possible the regulator is bad and the fuel is bypassing the injectors?

 

[chuzie]

Well if there was no residual pressure it tells me you may have a regulator issue or a pump/restriction issue. Even after a good 10 minutes of being shut off, I have at least 20 pounds of pressure; enough to cause a spray of fuel from the valve.

Oh, like a liquid filled Autometer fuel pressure gauge with a nice cup mount bolted to the hood. Probably overkill for most folks, but I specialize in overkill.

 

[Viperwolf1]

I get a slight smell of fuel in the vacuum line to the regulator... Is it possible the regulator is bad and the fuel is bypassing the injectors?

Open the return line and see if it sprays fuel out with the pumps on.

 

[Mountain Ram]

Open the return line and see if it sprays fuel out with the pumps on.

Pulled the return line and ran the pumps- fuel runs out... Doesn't spray out. Also pulled the regulator vacuum line and ran he pumps few times... No leaks there. I am going to wait until tomorrow to see if I can pick up a new FP gauge and start over.

I will check spark again, fuel pressure too...

It's just weird how it has come and gone with no rhyme nor reason... Engine was cold every time and started prior to or later in the day.

 

[Mountain Ram]

And of course it started right up this morning... No codes...

Frustrating.

 

[Mountain Ram]

Idled for a few minutes and shut itself off... And won't start again.

 

[Mountain Ram]

FWIW-
The fuel filter is new with the build. The low pressure pump is a universal model and the high pressure pump is out of an F250 (I believe), both were on the truck when running with the previous motor.

I have power to both pumps- checked with a test light when not starting. I can hear both pumps run and as noted in a previous post, I dumped the return into a bucket and I have fuel coming out when I hit the key and the pumps run- but it is not pressurized at this point.

I have spark and the plugs are not fouled.

 

[Viperwolf1]

What's the layout of the fuel system?

 

[Mountain Ram]

Stock tank and pickup to fuel filter. Fuel filter to low pressure pump, low pressure to high pressure pump. High pressure pump to explorer fuel rail with stock regulator. Explorer fuel rail back to tank.

No fuel accumulator, but prior engine ran without- no issues. Ran all day this past Sunday with no issues. Approx 6-7 gallons in tank- 5 new last night.

 

[Viperwolf1]

Stock tank and pickup to fuel filter. Fuel filter to low pressure pump, low pressure to high pressure pump. High pressure pump to explorer fuel rail with stock regulator. Explorer fuel rail back to tank.

No fuel accumulator, but prior engine ran without- no issues. Ran all day this past Sunday with no issues. Approx 6-7 gallons in tank- 5 new last night.

I had similar issues way back. Turned out the LP pump couldn't push as much fuel as the HP pump when it was hot. You might try just bypassing the LP pump.

 

[Mountain Ram]

I had similar issues way back. Turned out the LP pump couldn't push as much fuel as the HP pump when it was hot. You might try just bypassing the LP pump.

Is it a degrading condition with the LP pump? The pumps dont even get a chance to warm up when it dies now. I thought you had to have a puller (LP) pump to feed the HP, but the LP needed much higher volume. Should I look at replacing it? The fuel pressure gauge should tell me if this is the problem.

These pumps were on the truck with the old EFI setup and worked fine. With 30lb injectors and a much improved motor, I may be surpassing the pumps capabilities, but... How did it run all day Sunday with no issues?

Man I am so aggravated and confused and the Super Cel is a week away...

 

[Viperwolf1]

It could be degrading. I still use LP pumps but I changed them out to carter P4070. You will see it as low pressure at the rail.

 

[Bronco_69]

New 347 Build... WTF- no start again!

I had the same problem. It would start cold and then die when warm and not restart. The distributor was bad. I lost spark only when warm.

 

[Mountain Ram]

It could be degrading. I still use LP pumps but I changed them out to carter P4070. You will see it as low pressure at the rail.

Should have this understood tonight then. Do you run an accumulator? Looks like I can get one of those LP pumps at Oreiilys or Autozone should I need one, but if I need an accumulator, where can you get one on short notice?

I had the same problem. It would start cold and then die when warm and not restart. The distributor was bad. I lost spark only when warm.

I am very familiar with Dizzy issues- mainly TFI. I bought a new dizzy from Summit with a TFI module. The issue is the truck isn't even getting warm when it shuts off. It runs for less than 5 minutes- dizzy isnt warm to the touch. Also seems intermittent. Did it last week after the exhaust install and was doing it consistently last night... I have not completely ruled this out though...

 

[Viperwolf1]

I do have an accumulator but I don't think it makes a difference in this case.

 

[Nightstick]

New 347 Build... WTF- no start again!

I definitely hear something akin to a rocker rattle at high RPM... With the springs I have and roller rockers, I shouldnt have any valve float.

You're probably right, but do you remember what the open pressure is on your springs? I'm in the neighborhood of the mid 300s and I didn't get any valve float until about 5600rpm to give you an idea.

 

[Nightstick]

New 347 Build... WTF- no start again!

I don't think it would effect your fuel/stalling issue, but did you break-in your cam properly?