Fuel starvation
#12
12-26-2011 | 01:16 PM
Senior Member
Joined: Sep 2011
Posts: 767
From: Iowa
Hanky: are your referring to gorygoris: 1989 F250 Fuel Pressure ? You were stumped there as well, but he shows a fuel pressure regulator for a Holly carb.
Further I am thinking that this is jury-rigging with unintended consequences:
last week the petrol pump gave in again and i got it replaced. they removed the plug on the return line and squeezed the pipe smaller.
Quite possibly this narrowing of the pipe restricts fuel flow and throws off all adjustments you try to achieve.
Random thoughts:
On motorcycle carburators the shafts for the butterflies are wearing out letting in false air. Actually the throttle body holes get larger from wear. Check for vacuum leaks there.
There should be a choke, either manually operated or automatic by way of a small heater element. Worth checking.
There could be an intake air heater. Either a bypass pipe of the cooling system or an air duct bringing air to the cleaner warmed up by the header.
You must have the proper air cleaner or you would have too much or too little air coming in.
The needle valve must be working properly and must be adjusted correctly or you will have too much fuel or too little fuel in the bowl, which will either enrich or lean out the mixture.
The idle air control screw is important not only for the idle air mixture, but it affects the fuel mixture at partially open throttle as well.
There should be an acceleration pump which sqirts in extra fuel in as you step on the pedal. It must operate properly or you would have a stumbling engine as you step on it.
I hope this allows you to get closer to a smooth running engine.
By the way: if your engine has flooded a few times, please change the oil.
My experience with carbs comes from VW beetles, Renault 4, and various motorcycles. I am a pure hobbyist.
Further I am thinking that this is jury-rigging with unintended consequences:
last week the petrol pump gave in again and i got it replaced. they removed the plug on the return line and squeezed the pipe smaller.
Quite possibly this narrowing of the pipe restricts fuel flow and throws off all adjustments you try to achieve.
Random thoughts:
On motorcycle carburators the shafts for the butterflies are wearing out letting in false air. Actually the throttle body holes get larger from wear. Check for vacuum leaks there.
There should be a choke, either manually operated or automatic by way of a small heater element. Worth checking.
There could be an intake air heater. Either a bypass pipe of the cooling system or an air duct bringing air to the cleaner warmed up by the header.
You must have the proper air cleaner or you would have too much or too little air coming in.
The needle valve must be working properly and must be adjusted correctly or you will have too much fuel or too little fuel in the bowl, which will either enrich or lean out the mixture.
The idle air control screw is important not only for the idle air mixture, but it affects the fuel mixture at partially open throttle as well.
There should be an acceleration pump which sqirts in extra fuel in as you step on the pedal. It must operate properly or you would have a stumbling engine as you step on it.
I hope this allows you to get closer to a smooth running engine.
By the way: if your engine has flooded a few times, please change the oil.
My experience with carbs comes from VW beetles, Renault 4, and various motorcycles. I am a pure hobbyist.
Last edited by bluewind; 12-26-2011 at 01:25 PM. Reason: typo
#13
12-26-2011 | 01:36 PM
Senior Member
Joined: Jun 2010
Posts: 15,301
bluewind,I agree with you and everything you posted.
The carburetor fuel regulator system is out of my little reservoir of experience.
Whoever is working on the vehicle in question has some knowledge and they probably did what they thought would work , so I guess we'll have to wait and see if they can do it right and correct the problem.
The carburetor fuel regulator system is out of my little reservoir of experience.
Whoever is working on the vehicle in question has some knowledge and they probably did what they thought would work , so I guess we'll have to wait and see if they can do it right and correct the problem.
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