acts ;\like it's running out of gas

[GOW]

my 40 merc stock v8 with an elect. fuel pump acts like it's running out of gas around 55mph in high gear only.....I can drive around town any gear 40mph or so no problems....I can wind it up to over 50mph in second no problem. can rev it in the driveway no problems.....just high gear h'way driving.....I did just put a clear in line fuel filter in gas line between the regulator and the carb. filter is clear. i'm stumped...any ideas. thanks

[Mart]

Breather on the tank blocked??

Mart.

[GOW]

no ...but thanks

[FlatheadTed]

Pull the choke ,If it smooths out then it fuel starvation .

[GOW]

ok i'll try that

[L78CHEVELLE]

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What size fuel line are you runing and how much fuel pressure to the carb?

[bgarrett]

sounds like the fuel filter is getting stopped up or maybe someone put a plastic baggie in the tank

[GOW]

1/4" fuel line/3psi...........filter is clear.

[Ken/Alabama]

Have you checked the float level in the carb ??

[G.M.]

I'll go along with float level. As long as the fuel line has a .125 ID you will get enough fuel. The flow restriction hole in the needle valve is less than .100 so that's all the fuel you will get even if you put a 3/8" line all the way back to the tank. I bought a roll of 1/4" copper tube with a .150 ID and was making a fuel line from the pump to carb and discovered it was heavy wall tubing. I decided to try it anyway. It's been on for several years and runs normally. G.M.

[FRITZ47]

How long has the electric fuel pump been installed? I had a problem with Ethanol fuel in that it gradually swelled up the rubber parts of my electric fuel pump that I used for starting purposes. Eventually the car would not start (no fuel at all). We removed and bypassed the electric pump with a short piece of SAE 30 R9 fuel injection hose (Ethanol resistant) and the car has since been running fine on the factory fuel pump which was still in the car. That pump was rebuilt and hopefully Ethanol resistant parts were installed. When we buy new reproduction (made in China) fuel pumps, who knows what type of rubber components are used? This was mentioned some time ago on this forum.

Any rubber fuel line hoses (if not already changed) should be replaced with Ethanol resistant fuel injection hoses, as the older fuel hoses are not Ethanol resistant and will swell on the inside, causing all types of fuel-related problems. That might be a good way to start. If you do this, be sure to buy fuel injection hose (not ordinary fuel hose). Ask for 30R9 hose at any auto parts store - expensive, but eliminates future problems.

Attached are 2 pictures of my electric fuel pump that failed, which we cut open with a small rotary grinder. All of the rubber components swelled up into a solid mass and nothing could possibly pass through. Ethanol is one of our hobby's biggest enemies and can also cause problems in any other rubber components wihin the system (fuel pumps, carburetors, etc).

Also attached is a picture of a good bypass setup using an electric fuel pump for starting purposes only, if still using the original or replacement mechanical pump for normal operation. At the bottom of this picture (directly below the electric fuel pump) is a check valve, which is necessary.

Any time fuel problems occur, Ethanol fuel can often be most of the problem. I live in Ohio and we cannot purchase non-Ethanol fuel, and it is not even mandatory that the pumps be labelled as having Ethanol. Wait until the present 10% Ethanol is increased to 15% or more - the problem will be even worse. There are additives avaialble, but I am not convinced that they do much good, so I have gradually been replacing any/all rubber hoses and then having my fuel pumps and carburetors rebuilt with Ethanol resistant rubber components. It is a continual battle.

Fritz

[GOW]

WOW !!! pics are worth a thousand words.....lots of good ideas. thanks

[Jack E/NJ]

Fritz47>>>Attached are 2 pictures of my electric fuel pump that failed, which we cut open with a small rotary grinder. All of the rubber components swelled up into a solid mass and nothing could possibly pass through.>>>

I'm not sure what I'm looking at in your cutaway pictures? The black solid inside the metal canister looks more like normal potting compound to me.

Jack E/NJ

[36Bill]

I had a similar problem with my old MG, it was a bug that got into the gas tank and would plug the outlet at speed. Hell to find and fix, I tried just about everything. Or could be short on air, plugged air cleaner?
Good luck

Bill

[jdl]

A bad gas cap ( or non vented ) can cause your problem also. try a test run without the gas cap. also a clogged muffler can have the same symptom ( very rarely happens)

[TJ]

If you have the round adjustable dial type regulator that may be the problem. I had the same problem some time back and eventually, through the process of elimination, came to find that this regulator was the problem. I put a Holly regulator in line and no more trouble. The Holly regulator regulates the fuel with a spring loaded diaphragm. You can change the springs for the different pressure you need for your carb.

[Step-down]

I don't suppose you just installed the electrical fuel pump did you . Is this to prime the motor then full operation is with your stock mechanical fuel pump. I'm fishing here because some electrical fuel require a by pass do to the fact the stock pump can't pull thur the electrical pump on hi- flow.

[GOW]

it was running fine . the problem started monday

[41ford1]

Your problem may be caused by the tank pickup getting blocked (ref 36Bill). I had the same problem with the truck. It had been run on straight gas then stored a few years. The E10 loosened the varnish causing blockage. It only happened after running at speed (40-50MPH).

[GOW]

PROBLEM SLOVED !!!!!!!!!!!!!! I was sittin there looking over my 40 .....and all of a sudden it came to me....I put a new gas cap on ......went over opened the cap and it went whoooosh !!!!!!. I put a non-vented cap on in place of the org. cap which was vented !!!!!!!!!!!!!!! THANKS TO ALL WHO GAVE ME REPLYS....they got me thinkin !!!!!

[TJ]

jdl hit it right on the money about the fuel cap.

[GOW]

He sure did !!!!

[FRITZ47]

Originally Posted by Jack E/NJ

Fritz47>>>Attached are 2 pictures of my electric fuel pump that failed, which we cut open with a small rotary grinder. All of the rubber components swelled up into a solid mass and nothing could possibly pass through.>>>

I'm not sure what I'm looking at in your cutaway pictures? The black solid inside the metal canister looks more like normal potting compound to me.

Jack E/NJ

I have never cut open a new electric fuel pump, so cannot determine what I am looking for. However, after removing the "defective" pump, I huffed and I puffed and I still could not blow through the pump. Prior to installing this electric pump 2 or 3 years prior, I was able to blow air through the pump (without huffing and puffing). Based on this, feel that the pump failed and I attribute much of this to Ethanol in the fuel.

Fritz