VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc fuel pump signs of going out?

What if any does a fuel pump give that it is going out? Car is a 454 with a AC Delco 40770 fuel pump. Thanks

Hold it flat to the floor from a start. If the pump is not pumping enough gas the engine will cut out by 60MPH when the carburetor runs low on gas. A plugged up fuel filter will give the same results. The "real way" would be to do a volumn test and pressure test with a pressure gauge as per the shop manual.

The most common is gas coming out of the vent holes on the side, they can also leak oil there to. The other would be stalling out under heavy loads, then you need to check pressure and volume.

I don’t know if this is related or not, but the car is hard to start today. But the doughnut gasket blew out on the passenger side. That wouldn’t make it hard to start would it? thanks

No that would not cause a hard start. You need to check the fuel pressure and volume. What year is this in, does it have points and if so check the dwell, if it is off much it will cause problems.

It is in my 1971 corvette, 454 and it does not have points. Any more. The fuel pump is about 25 years old, I have feeling that it is going out just do to its age.

What are your hard start symptoms? Cold or hot have you checked the choke to see if it goes closed? If you poor a little gas down the carb does that help?

I kinda like your way Gene! don't try this at home with a 454, get out of town and blow away some of those Dodge Rams!

Let it off after you peg out the speedometer, if it don't stumble!!!!
I did that with our 68 Impala 327 275 HP...Grandma, liked to of had a hissy fit! It is her 68, by the way.....

I looked in the carburetor and gave it a shot of gas , and it did not look like a good stream came out. The car was that it was just spinning over and not firing. I will check the cap tomorrow to see if I am getting fire. It is always something with old cars. You take them out for a drive then they refuse to crank the next time you get in them.

What does it have for ignition, aftermarket or later factory HEI or is it the factory transistor, I am not sure that was still an option?

I took the points out and put in one of those electronic point eliminator kits in

I would like to say that I put in a set of Pertronix Ignitor electronic module and the magnetic whatever in our 68 and I kept a new set of points, condenser combo set just for to be safe. I had problems, died at a traffic light in busy Arlington and had intermitenent hard starting. put on a newly Holly rebuilt Qjet, fuel line in carb filter, add on in line filter,new wireing, cables. The problems quit when I went back to the original points & condenser set. With the window in the distributor cap and using the special point tool allen wrench it isn't that much of a problem to set the points then when I got back to the shop throw on the dwell meter and fine tune for the best performance. The gas milage is better with the points for me, go figure. Anyone want to buy a new Petronix set with a new 40,000V Flame thrower coil for a 68 327, 275hp with AC & AT? (I bought two sets when I converted)1 is new in the box and the other one went into the trash!

Yeah, I hear you I might go back with points. I have heard from other people that have had problems with the conversions. Then you hear, that some never give you trouble. At least with points, you get a warning, that they are going out. But the electronic, when it goes you don’t get any kind of tell tell signs. It just goes kaput.

I've had the pertronix Ignitor in my 39 for over two years with no trouble. And I live with,( MURPHY'S LAW )if it can go wrong it will go wrong GOOD LUCK....

We put a Pertonix in our 1970 Impala and it lasted one week!

On the other hand, a good friend of mine put a pertronix on his otherwise totally bone stock 56 210 265 2 barrel PG wagon about a year and 1/2 ago and has been trouble free. He says it's the greatest thing since xxx.

As the recent 3-4 posts indicate, I guess it's like every thing else. Sometimes things work out and sometimes they don't....

I am still having starting issues with my 454. My thinking is the fuel pump is going out, but I am not sure it might be carburetor issues also. I took the lid off the breather and watched it shoot some gas into it. It did not shoot a whole lot. So I got in a cranked on it finally started. So I went an worked the throttle by hand to watch the carb and see how much gas would come out, and it was not much but it acted like it had a flat spot an wanted to die. I don’t know if it is the pump or that Q-jet carb? Any thoughts ideas? Thanks

There are two issues with a Qjet that I have experianced, the bottom of the float bowl is so thin that the welch plugs corrode and leak out the fuel after the engine is shut off, then it takes a lot of cranking for the fuel pump to load the carb. if you have both a worn out fuel pump or fuel pump plunger rod and a leaky carb it causes poor starting after the car sits for a while.

One of the long term problems I have experienced with Q-Jet's is that over time the float will absorb fuel. Even if you set the float height correctly the fuel level will be too low due to the increased weight of the float.

I had a '72 Corvette with 100,000+ miles on it. When the car was about 10 years old you could feel the weight difference between new and old floats if you held one in each hand.

Rusty:
This shop might be able to answer your carburetor problems,very friendly and knowledgeable.

http://thecarburetorshop.com

Question, If the float soaked up gasoline and was too heavy would not that cause TOO MUCH fuel into the carb?

Yes, they are very helpful. I have talked to them on other matters.

In the situation I described I simply replaced the float and the problem went away.

I was offering that as another item for LKS4541 to troubleshoot.

Thanks!

Hi Mr. Mack,

I apologize for not responding to your note. Somehow I missed it in the postings.

Yes, your analysis is correct. The heavy float does cause the fuel level to be too high in the float bowl. This can create starting problems because the engine will more easily flood even without excessive pumping of the accelerator.