Fuel pump: What would happen if someone reversed the two gas lines on the pump?

Question

on the top of the pump where the three line connections are...as you are aware of im sure, two of them are for fuel...incoming and return...what would happen if those lines were to be installed backward? I had my pump replaced, and afterward it will not idle or run properly...the problem is mostly at idle though, and when I accelerate there is black smoke (running rich). What might be wrong? Since the only thing different is that the pump was replaced, im thinking something with that installation went wrong. Its a 97 Chevy Astro

Answer 1

HI

sounds like it flooding out.. Might have a bad fuel pusher regulator causing it to flood out. If your EFI.  and if your carbed you might have to re set the float level.

Good luck

Tim

Answer 2

Buy a Hanes manual and crawl underneath check that out yourself.

I don't think your car could run with the two switched, but if it could, c**p will be being pushed out of the fuel filter back into the pump and tank...

Not sure what emissions control fuel stuff is on that van but can't see it being a good thing... if it would work at all.

Was it a brand new pump or used...

Answer 3

a few problems that i see with that situation. the lines coming off of the fuel pump are three different sizes, so it should be really difficult to mess that part up. if you were able to do that the return line does not reach the bottom of the tank so getting enough fuel to pressurize the system to the 50+ psi that is needed would be interesting to say the least. after that the pressure regulator should work in either direction, it is a glorified hydraulic circuit. the best opportunity that i see is for you to take it back to where the pump was put in and find out what is going on. you could have a bad pump, a loose connection at the electrical side of that pump, or a few other problems. if your problem is an idle control issue then you might look into a diagnosis for that. you could be chasing your tail on the fuel pump issue.

Answer 4

Bistro, it would be highly unlikely that fuel pump lines could be improperly installed. Simply because they are different sizes. 2 of the lines are pressure and return and are of different sizes. The third is an evap line and uses a different fitting all together. In essence, they are "idiot proof"

Since you said it is running rich, one thing comes to mind. If the fuel return line going to the tank was kinked somehow during the reinstallation of the tank, it would certainly cause the system to go rich. This could be verified by checking the fuel pressure. If it is about 90+ psi, then the fuel pressure isn't being regulated back to the tank. I would immediately suspect the return line is kinked.

But I am suspecting you might have another problem. Your 4.3 liter engine in your Astro uses pintle injector poppets. GM has had several technical service bulletins on these. The poppets tend to hang open and supply the cylinders with fuel when they should be off. You can verify this with a simple test. Hook up a fuel pressure gage and turn the key on.But don't start the van. See if the fuel pressure builds and then drops off within a few seconds. Do this several times and if the pressure drops each time, try to start the van on the last try. If it is very hard to start and blows a lot a smoke, then you know the poppets were leaking down during the test.

If it is indeed the poppets and you are the original owner of the van, I would talk to GM about some warranty assistance.  

Answer 5

he car would not run at all.It would be just like you have a bad fuel pump.

Answer 6

The pump is not hooked up backwards. If that were the case, it would only draw air and not run. If it's running rich, the carb needs adjusting. It's a new pump so it's getting the proper mixture of fuel but the carb isn't adjusted to accept it. This is all in theory of course as I'm not there to actually see it.