Inliners International Forums General Discussion Engines 235 Fuel Pump Problem

Hi,
I'm having a problem with fuel supply. Driving around the other day I had a sudden loss of power.
Next time i tried to start the car it was not getting any gas. I could see in the clear fuel filter that it was bone dry. I proceded to replace the Fuel Pump but gas was still not flowing very strong. When i dissconnected the line from the carb gas was barely trickling out.
I re-connected the line and still no gas. Finally i took out the filter from my Rochester and lo and behold it started. I took a drive and still had no power though...when i got back i noticed that there was barely any fuel in the clear filter. Previously the Filter had always been at least half full of gas and i could see it pumping when i hit the throttle.

Mechanical fuel pumps are pretty indestructible so my question is why aint it pumping?

Just a little history. I had the renu process done on my tank and blew out all old lines when i replaced the tank.
I just put in a brand new starter and electronic ignition and the car starts and idles fine. Problem is no power! I'm guessing it's fuel supply but am open to other suggestions.

1) Could having a blocked filter in my carb have caused the pumps to lose power.

2) Could the cam lobe have worn down so that the pumps aren't pumping as much as they should.

3) Is there a more powerful mechanical pump i can use for a 235...or should i go electric?

hello..i do not know the specifics of your inline 6, but i recently added an electric pump to my 292...WOW what a difference!!!!...seems the last 2 mechanicals i bought just didnt work well...by changing to electric i have quicker ,easier starts and runs great...I also have a fuel regulator...
Carter makes a universal pump-if can be bought at NAPA....I will get part # later....
hope this helps.....

hello..here is pump....

http://cgi.ebay.com/ebaymotors/ws/eBayIS...ssPageName=WDVW

Dear RS;

You might want to make sure the tank is vented allowing the fuel to flow freely to the pump.

Rarely does the cam lobe wear down where the pump won't function or electric pumps needed.

Good luck, John M.....

Ran in to a similar problem about a year ago with a 56 Chevy car running a stock 235. Everything from the fuel pump itself to the cam lobe was blamed. As it turned out the short rubber flexible fuel line that attaches to the tank fitting did not have a clamp on it and as time went on the hose simply lost its snug fit on the tank barb allowing the pump to pull air instead of fuel. Since the hose connects at the top of the tank the car never leaked any gas to give a hint of the problem area. Interestingly enough one know it all temporarily mounted an electric fuel pump and the car ran fine the entire time that pump was being used. The explanation of course is the electric pump moved a lot more volume than the stock pump so the mix of air and fuel was enough to keep the carb full and the air drawn by the pump was simply vented out the carb bowl.

It's sometimes the little things that kill you so double check all your soft line connections before condemning the fuel pump.

You could possibly have a problem related to the tank sealing process and material or a damaged pick up tube in the tank.

What kind of car and tank are we talking about? Older cars had the pick up tube coming out about half way up the side of the tank and the bottom laid right down on the bottom of the tank. They are non removable and some tank sealer could very well have ended up in it making a blockage.

Mike

hello...you should try an electic pump...until you do, you will not realize the huge difference......

There are pros and cons for electric vs. mechanical pumps. Mechanical pumps operate at engine speed and are automatically pressure regulated. They also stop when the engine stops. One down side is that a diaphram leak can cause fuel to enter the pan where it has been known to explode, another is having to crank the engine too long when the fuel has been emptied and then replenished. Electic pumps either need to be adjustable for pressure or require a separate regulator. To be safe, electric pumps should be equipted with a low oil pressure shutoff (bypassed during starting) or with a rollover or crash sensor.

There should be no difference in performance between the two unless you developing more that twice the rated horsepower IMHO.

Bald E. Gull

I have the same problem as you rocketsociety. I tried an electric pump & didn't make any difference. I beleive my car is running out of gas when I floor it. My car runs fine at normal speeds, but when I floor it, it runs like it has a lean condition. I have a brand new mechanical pump on with a holley/weber 2bbl plus new filter.
The next thing I am going to do is change the fuel lines all from tank to carb and clean out my tank with muratic acid and change the sock out on the pick-up.

Well i do have a ventilator tube that comes up from the filler tube. This is a '59 El Camino...not sure if there should be any other ventilation on the tank?

Thanks for all the other tips. Electric pump is an option but i'd like to isolate the probelem otherwise i'm just masking another issue.

I noticed that the carb wasn't bolted as tightly as it could have been to the manifold so i've tightened it up and checked the vacuum lines. Also I took the water heat setup off my intake as I only put it on there for my Holly/Webber that I took off because i wasnt happy with it. I never had heat on the manifold before and i didn't seem to have any problems with my 1bbl Rochester.

I'll test drive tonight and see if that did anything.

interesting comments....there was a Tremendous difference in my street 292 with an electric fuel pump-....I have heard others doing this swap from mechanical to electric for years and I finally did it...and wowww what a difference!!!!...
wonder if is due to the specific pump I am referring to or is related to the whole system?..I also upgraded from 5/16 stock steel tube fuel line to 3/8" rubber hose.....

also to make note-my street 292 is not stock....

Dear RS;

Make sure the cap is a 'vented' one. The line you speak of is an 'overflow' tube & won't vent if the cap is wrong.

With the cap off, pull the line(imput)to the pump. With the vehicle sitting level it should have a full flow squirting at least 1" or more.

If not; You have a restriction in the tank or the line. Repete the proceture (if restriced)by removing the line from the tank & checking. If still restricted It's in the tank or pickup tube somehow.

I can't recal if the 'pickup'tube is part of the fuel guage (sender)or not. If so, some models have a filter that is part of it and sometimes clogs. Also the pickup tube itself (inside tank)can clog.

Remember; Tanks are usually above the pump so the fuel can "gravity feed" with It's weight (8# per Gal.)pushing it.

It's just a "process of elimination". You'll find it.

Good luck, John M....

With regards to Lee's post

( interesting comments....there was a Tremendous difference in my street 292 with an electric fuel pump-....I have heard others doing this swap from mechanical to electric for years and I finally did it...and wowww what a difference!!!!... )

If the original fuel pump was not able to keep the carb float bowl full then any replacement pump whether electrical, mechanical, or hamster powered would make the difference you describe if it was able to supply the required volume. Pressure is only used to overcome any restrictions in the piping system to get the fuel to where it is going and it is the volume that keeps the carb supplied.
I have run Carter and Holley mechanical race pumps and both Holley street and race electric pumps and if the fuel requirements of the carb system are being met I honestly can say that as a racer / driver there is no way you can tell what is feeding that carb except for the sometimes annoying hum of an electric fuel pump.

I am currently running an electric pump on my very warmed over 250 and it feeds an Edelbrock 500cfm carb. The only reason I built it with the electric pump was for a cleaner appearance with underhood fuel line routing and so down the road if I choose to change to a 292 based engine I can run the cam that is now in the 250. And yes, the pump is wired through an oil pressure switch so it will not stay running if the engine stops. This switch is bypassed with the key in the start position while cranking.

Mike

Guys...thanks for the tips. Here's an update to the saga. I tried everything short of an Electric pump and even though I'd put a few gallons of gas in the tank I decided why not fill the tank and see what happens. Well sure enough as soon as i filled the tank my Fuel pump starts pumping like it used to. Finally my filter was full and i could see gas squirting in there like gang busters!

Driving away from the gas station I could tell right away that my drivability was back to where it used to be. I no longer bog down when i hit the throttle.

I happily drove down the road to a friends warehouse where I was gonna do some body work.
We were all set to get out the torch when I smelled gas! I looked under the car and gas is dripping down from my sending unit like crazy!!!!
On further investigation i found that gas was leaking though the threads of one of the screws holding the sending unit on to the tank.

I had recently had the tank coated with the Renu process and I had my mechanic drop the tank and put it back in. It seems he failed to put a washer on one of the screws and I guess it wasnt seated very well causing gas to leak past the threads.

To make a long story even longer...I took it back to the garage and told him to fix it before i sued him for almost kiling me...not to mention the headaches it caused me!

Anyway from this fiasco my theory is that when I only had a few gallons in the tank, that leaking screw hole on the sending unit was above the gas level and therefore was sucking in air...reducing the pressure so that the pump wasn't powerful enough to suck in enough gas. When the tank is full the hole is submerged in gas so that it doesn't suck in air....so i have enough pressure and the pump works like it should.

Does this sound like a logical explaination?

The leaking screw wouldn't cause the problem. All it did was act as another tiny little tank vent. More likely it was the few gallons of gas in the tank were not enough to completely cover the pick up screen so the pump was sucking a mixture of air and gas. When driving this little amount of gas sloshed around making the problem worse as it left the pick up completely exposed util it sloshed back over it again.

Well at least now you know how far you might be able to travel before you start running out of gas. LOL


Like I said earlier - its the little things that drive you nuts, in this case too little fuel in the tank. Glad you didn't have a major problem to fix.

Mike

I once had one of these that "made us crazy".

I/we pulled the tank again and found a golf ball inside.

JM...

yea I guess you're right. It was strange that the pump started pumping stronger and car ran better when the tank was full though.

The rubber hose connecting my gas line to the sending unit was probably sucking some air so I changed it and i found that my timing was a little retarded as well.

I think i'm good now...but having multiple things going on at the same time made this a tough one!

I just cleaned out my gas tank. Was all gummed up on the inside from sitting with about a half tank of gas. The muratic acid cleaned it some, but gonna need a new tank someday. Anyways, I found that the sock on the end of the pick-up tube was almost completely clogged. Also, the tube itself was clogged on the inside. I cleaned it out and put on a new sock. I also replaced all of the fuel line from front to back. Now I am getting full pressure to the carb with the mechanical pump. My clear fuel filter fills up completely & the car runs way better. :p