Fuel filter before or after pump - Third Generation F-Body Message Boards

TNT_Z28 · 05-18-2010, 10:07 AM

where should i mount the in line fuel filter i have. before the fuel pump inside the fender or somewhere between the fuel pump and carb? on my old carb the filter was actually in the carb.

five7kid · 05-18-2010, 01:59 PM

The in-line filter should go between the pump and carb.

An '87 should have an in-tank pump. Is it operating? Has it been removed?

TNT_Z28 · 05-18-2010, 03:16 PM

my car came with a pump on the side of the block. it was origanally an lg4.

would it really have 2 fuel pumps?

five7kid · 05-18-2010, 11:05 PM

Yes, the '87 LG4's did. An electric pump in the tank, and a mechanical pump on the engine. If the in-tank is not operating, the engine-mounted mechanical will not be able to keep up.

TNT_Z28 · 05-19-2010, 09:32 AM

thats f***ed up. now ive got a whole other headache to figure out

five7kid · 05-19-2010, 09:51 AM

Actually, it's a very good system. Pumps don't pull well, but they do push well. Having the pusher electric immersed in fuel in the tank prevents vapor lock and fuel starvation better than any other option.

Auggie · 05-19-2010, 11:29 AM

Yup, he's right for the reasons he stated. I had one installed in my 84 under warrenty for that very reason. Vapor locking. You can check the intank elect pump by disconnecting the fuel line(remove gas cap) from the mech. pump inlet and put the fuel line into a container. Find the oil pressure switch (mine is located by the oil filter) turn on the key and jump the oil pressure switch.

Auggie

TNT_Z28 · 05-20-2010, 12:14 PM

what if its not working? would i be better off removing it and getting a high volume mechanical or fixing that one?

also would the intank pump have a relay? if so i think i removed it.

five7kid · 05-20-2010, 02:02 PM

The in-tank pump does have a relay. If it isn't there, I'd either put it back, or drop the tank and remove the in-tank pump. There is a sticky in the top section of this forum on how to convert to a manual pump type pick-up.

Personally, I'd want that in-tank pump working if I already had it. Even if I had to drop the tank to replace it.

TNT_Z28 · 05-20-2010, 09:27 PM

that makes sence.

before i removed the relay, i always heard a buzzing noise coming from what sounded like the rear axel area. it drained my battery whenever i left the battery plugged in, so for a while i unplugged my battery at night.

now that i know there is an in tank pump, im sure it was that. Would that mean that the pump was bad? should it be replaced?

i saved the relay. is there a way that i could wire that without connecting it to the computer?

shelad · 05-20-2010, 09:32 PM

Hey fifty7kid. I have a 86 Camaro. It started life with a 2.8. Not only is that long gone, so is the computer and wiring harness. I put a 350 in it with a th350. I'm running the mechanical fuel pump, but I see that you recommend using both. Is that a standard statement,or just for a particular application? My electric is still in there and relatively new. Is there a way of making it work with no computer, or anything? Also, my fuel pump losses pressure as its driven. Goes right to zero. When it cools, it starts at 61/2 - 71/2. I haven't bypassed the old stock filter yet. Any ideas? Thanks Larry

five7kid · 05-21-2010, 11:32 AM

You can rewire the in-tank to work.

RyanEricW · 06-16-2010, 05:36 AM

Quote:

Originally Posted by shelad

Hey fifty7kid. I have a 86 Camaro. It started life with a 2.8. Not only is that long gone, so is the computer and wiring harness. I put a 350 in it with a th350. I'm running the mechanical fuel pump, but I see that you recommend using both. Is that a standard statement,or just for a particular application? My electric is still in there and relatively new. Is there a way of making it work with no computer, or anything? Also, my fuel pump losses pressure as its driven. Goes right to zero. When it cools, it starts at 61/2 - 71/2. I haven't bypassed the old stock filter yet. Any ideas? Thanks Larry

Honestly, not sure about the filter being the issue. If filters can really be too small, or have a unwanted restriction it would boost pressure and lower your volume. Someone want to clarify about the filter?

What it sounds like though is a volume issue. Did you change all of the fuel lines when you swapped motors? The diameter of the fuel lines could be different (smaller) giving you a smaller volume, creating your issue.

Quote:

Originally Posted by TNT_Z28

that makes sence.

before i removed the relay, i always heard a buzzing noise coming from what sounded like the rear axel area. it drained my battery whenever i left the battery plugged in, so for a while i unplugged my battery at night.

now that i know there is an in tank pump, im sure it was that. Would that mean that the pump was bad? should it be replaced?

i saved the relay. is there a way that i could wire that without connecting it to the computer?

Replace the relay and see if that works. IT is possible that the relay was stuck in the ON position.
If you don't know what a relay is, it is basically an electromagnetic switch. It allows you to control larger wire (big amperage)(fuel pump), with small wire (low amperage)(switch or small wires under dash). It is nice because it costs less, relatively less weight, and you have smaller wires under the dash = less potential hazard of a fire.