Hot Rods Fuel System Gurus - Need Advice (stranded in Rural Oklahoma)

Running a SBC with a Holley, no spacer - aluminum intake. Engine ran fine for about 100 miles, then began to sputter. When i checked the filter there was some sediment, and the gas was bubbling on the side of the pump facing the carb. I stopped and swapped the filter (bought some spares - and was fine for another 30 miles or so. There is no sediment in the filter, but it cuts off after a few miles of driving and will run again soon after.

I thought maybe the pump was bad - so I replaced it. The country Auto zone didnt have a mechanical replacement - so I plumbed in an electric pump. The truck starts and runs fine - but after 20 miles or so it sputters and dies. Then its starts fine again/repeat ...


My thoughts/observations:

Maybe I need a spacer under the carb. Perhaps vapor lock.
I think the bubbling of fuel may indicate a small split in the line.
Consequently, it is not bubbling after I put in the electric pump.
The bubbling is not boiling - the filter is not hot to the touch.
Possible ignition issue?

Any other thoughts?

I'm tired going to sleep on it and hit it again in the am.

 

Sputters , dies and....

- then immediately starts right back up?

- after sitting ? How long ?

What type of ignition are you running ?

 

Like an hei ,
the moduels are know to act up when they get hot. Especially if they are mounted with out the heat sink paste.

A while ? That's could be 20 seconds to 20 years. Helps if you but a time speced in mins.

You know I call for a pizza and they ask what's size I want. Around here there's all different size "large" pies.
So I ask them how big is the pie? They say 8 slices. I say great, I can cut a house into 8 slices. Is your large a 12" or is the 12" your medium. I don't know let me go measure ,,,

I'd imagine it needs to sit long enough for the module to cool off . If it starts immediate you have a different problem.

 

A while = 10-20 min. Do you think its ignition related and the air bubbling in the filter is a non issue?

 

Not saying this is your problem but it's easy to check,,look at the short rubber gas line between your tank and metal line,,,it could have deteriorated and cracked,,it could be ****ing more air than gas.

It happened to me recently,,this ****py gas can kill rubber. HRP

 

http://www.carcraft.com/techarticles/ccrp_1302_hei_distributor_tune_up/photo_04.html

Air bubbling in fuel won't keep it from starting, Or make it stall. It could cause you some upper rpm fuel starvation, running lean and such. You said filter or fuel was not hot. The pump could be ****ing air but i do not think thats what's causing your trouble.

Cool down period allowing it to start again is 97.5% its ignition related and the symptoms you describe are text book HEI moduel related.

 

Try it with the gas cap off!!!

 

Fuel lines can **** air but not leak fuel.
It's a weird phenomenon that's hard to understand , and hard to believe until it happens to you.

A bad vent in the tank probably won't let you get 100 miles, then 30, then 20.
After it sits all night, the module might get you another 100 miles or it might continue on its decline pattern.
I'd put money on the module being in its last stages of life and this is its death roll.

 

Thanks - I am not HEI savvy - but the reading I am doing online is right in line with your suggestions.

Reading on repair/swap now.


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Filter on the pickup in the tank? When it won't start, try a bit of fuel in the carb and see if it will run. If it runs, probably fuel related and not ignition.

Bad coil? Tend to break down with heat. My experience with modules is they pretty much go dead and stay dead.

 

Vapor lock

 

If you suspect it is vapor lock; the antique car guys run one gallon of diesel fuel to a full average size gas tank. They claim it works.

 

Vapor lock USUALLY will not occur while driving at speed because the fuel moves through the line faster than at idle and doesn't have the time to heat up into a vapor. Vapor lock USUALLY occurs at idle, slow speed or after sitting. And it's pretty hard to vapor lock while running an electric fuel pump.

 

Having experienced troubles with similar symptoms, I'd check the primary circuit wiring to the coil VERY carefully. Circuit making and breaking due to vibration can be frustrating to diagnose. Bad splice done in the circuit when an engine swap was done much earlier, loose push on connector at the coil, frayed wire on the backside of a harness connector near the coil, and a couple of duff ignition switches come to mind as giving me the most grief until I finally found the causes.

 

Are you running an ammeter? If you are might want to byp*** the ammeter. They do go bad, will cause an open in your primary circuit. Check it out, it's worth a shot.

 

Good advise here.
A squirt of fuel, carb cleaner or starting fluid will tell/decide for you if its fuel or ignition related.

Coils do come and go related to heat.
Those hei systems have a few inherent problems, but a few tune up parts and they get right back with the program for a bunch more trouble free service.

 

If it's not your HEI, may I suggest the sealant in the tank is peeling off and clogging the pickup tube...that is, IF you've ever had the tank cleaned and sealed.

It happened to me in my '55 Cadillac, 5 years AFTER I had the tank cleaned and sealed, on a trip to the Midwest from Denver showed me that the sealant is not permanent...acted like the car was out of gas but it'd restart and run for about 10-20 minutes at slower speeds...then die like it was starved of fuel. Nothing I could do about it til I got home -165 miles away. Took almost eight hours to go that distance at 30-40 mph and plenty of stops and starts. Pulled the tank and found sealant clogging ALL the filters (I run three).

I hope that isn't your problem and you get it fixed soon...

R-

 

Ethenoyl

 

90% of fuel problems are electrical. Change the module, cheap and easy and at least you rule it out.

 

How old is the fuel pump?

posted via smoke signals made with a Mexican blanket

 

Well - coil and rotor replaced. The store did not have a cap, do I cleaned the contacts - there is no pitting. I made it about 50 miles. Since it was not the fuel pump - I removed the temp electric pump and now the truck runs better.

Same thing - truck sputters and dies this time after another 10 miles. On a whim, I reached out and took off the cap - no difference. I am looking at the filter as air bubbles in it ...


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As I have mentioned a couple of times, there is probably **** in the carb and under pressure it clogs up and then when it sits, it un blocks enough to drive a few more miles before it clogs up again. Take the carb off pull the bowls clean them out, change out the filter and I bet your ready to go. With that setup on the truck there is not much else it could be, its pretty old school. Fuel or spark, that's all it could be.

 

When it will not start - Do you understand how and why a squirt of carb cleaner or starting fluid or gas will tell you if this problem is fuel or ignition related ?

http://easyautodiagnostics.com/gm/4.3L-5.0L-5.7L/distributor-mounted-icm-tests-1

 

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There was sediment in the filter, If some made it through and into the carb that is probably the problem. Had this happen to me on a couple of old cars in the past and clogged carb was the problem. At least its a Holley and easier to check and fix than most.

 

So did you make it home?
Pushing?
Stuck and waiting for Monday ?

 

I made it - tired. In the end it was a combination of both fuel and possibly ignition issues. I am going to tear into it and give it a thorough tune up after I get some rest.

Thanks to all who made suggestions - I appreciate the help and advice.

 

An electric fuel pump provides a relatively even flow of fuel regardless of rpm or the engines requirement. A mechanical pumps out put varies with rpm to match the engines requirement. So earlier you said it "ran the same" ( from the road - I understand that.) with either pump after 20 miles or so.

Now with your hind site hypothesis is that one situation is fuel starvation do to sediment and the other is fuel overload due to excessive fuel amounts at throttle. Starvation and over load have different symptoms. One idles well but dies on acceleration, the other runs well at WOT and loads up or won't run at idle at low speeds. Not the same for sure and certainly won't matter much letting it rest in either scenario.

 

If 90% of fuel problems are electrical wouldn't that make them electrical problems????