Truck engine fuel problems?

Puller10001 · Mar 31, 2015

Have a 1973 dodge w200 with a 360, has 4 barrel holly are which is only a few years old, has always ran good until the last few days when you
get to about 45 mph and kinda get on it to get going faster it hesitates and bogs out of it, will die if you don"t let off, when you let off it catches
it"s breath and will sometimes go or will hesitate again. But sometimes you can run it up to 65 mph and it"s fine, sometimes it bogs sooner than
others, fuel filter is fine, only problem I noticed is the clear glass filter I have you see threw sometimes it keeps it full like it should and
sometimes it squirts just a little in when it"s running and then another little splash etc, is my fuel pump bad? And only working half the time the
way it should?

notjustair · Mar 31, 2015

Fuel pump is where I would start. It is needing the most fuel at that speed and runs the carb dry. By letting off you let the pump catch up and then it runs fine.

the tractor vet · Mar 31, 2015

Well first i would run a pressure test on the fuel pump and you Should come in someplace between 4-7 PSI . IF that checks out next place i would look is the power valve in the ft. metering block . Also check and make sure your tank vent is working . Also check float bowel fuel level on both , check vac. advance on the dist. Unless Holley has improved there power valves over the years they never like any gas with Al-ki-hol in it and it would eat power valves. Another sign of a defective power valve is long cranking on start up .

4play · Apr 1, 2015

Check the things mentioned above but a couple other things I have seen in the past are cracked, or loose fitting fuel line on the suction side or before the pump. Fuel pick up restricted in tank (sock).

Sprint 6 · Apr 1, 2015

As others have stated, check fuel pressure. I would bet the fuel pump pivot is worn out or broken, 360 fuel pumps have a long lever that puts lots of pressure on the pivot.

Side note, ditch that glass filter. Those are a weiner roast waiting to happen.

ditchwitch · Apr 1, 2015

Check the power valve in the carb ,the old hollys if they ever backfired they always messed them up

rustyfarmall · Apr 1, 2015

A weak ignition coil, or faulty spark plugs can cause those same symptoms.

GVSII · Apr 1, 2015

(quoted from post at 18:44:55 03/31/15) Fuel pump is where I would start. It is needing the most fuel at that speed and runs the carb dry. By letting off you let the pump catch up and then it runs fine.

Fuel pump is a good place to start but in addition to a pressure check I'd also do a flow check.Good idea to check the power valve as said.
An intermittent vacuum leak could also give the same symptoms.

J.Wondergem · Apr 1, 2015

You could try a electric fuel pump. I had the lobe wear off that runs the pump leaver.

Steve@Advance · Apr 1, 2015

Check the rubber hoses at the tank and before the pump. Could be rotted and cracked. Look the pump over for leaks, there is a vent hole, if it's wet, the diaphragm is leaking. Take the fuel line off the carb, slip on a section of rubber hose, direct it in a container and start it up, see what kind of flow you have. Should give a full stream pulse every time the pump cycles. If there is not a return line, the pump should hold pressure once it's shut off.

If the flow volume is low or blowing air, that's a sign of cracked hoses, sucking air somewhere, restriction in the pick-up sock, or bad pump diaphragm.

If the pressure is low, that's a sign of a bad pump.

Truck engine fuel problems?

Puller10001

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notjustair

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the tractor vet

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4play

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Sprint 6

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ditchwitch

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rustyfarmall

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GVSII

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J.Wondergem

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Steve@Advance

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