1998 GMC 4.3L - Excessive cranking after fuel filter change?

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Just swapped the fuel filter on my cousin's 98 GMC C1500 4.3. ~4-5 year old unknown filter off, Microgard filter on. No issues prior to changing the filter. Immediately after changing it, it cranked for a good 8-10 seconds then fired. I said "okay, it needed to replenish the lost fuel in the lines/re-prime. No big deal." No leaks. The old filter was leaking black fuel out of the "in" side, so it was clearly overdue.

Now EVERY cold (50-75 degree temps) crank takes 5-10 seconds before firing and he complains of smelling fuel, and it's quite strong. When warmed up, it cranks like normal. No issues. Prior to the filter change, every start took less than 1 second.

Surely this means it's a bad filter...right? These issues seem backwards from what they should be. These sound like before you change a fuel filter. Not after. If it's not the filter itself, what could it possibly be?!? It doesn't make sense that it would magically start showing unrelated problems at the exact moment the filter is changed. Any ideas? Thanks in advance!
 
The fuel pumps in that model year GM and prone to failure. Althought eh fuel filter was just swapped, I would be looking at the fuel pump. If it is the pump, Delphi frpm RockAuto is the only replacement I would consider.

Also, I can't say on the 1/2 ton pickup, but on the 98 S10 the fuel pump is grounded exclusively at a mount with the rear driver side tail light. A horrible design. I would quickly check the fuel pump ground before I did anything else. BTW- the ground wire is like 20 gauge or something, GM really skimped on the ground wire in size and distance, very disappointing .
 
If I had replaced the filter and it acted as it did after. I would suspect that the filter connections are sucking in air.
 
Originally Posted by Ursatdx
Is it possible the FF was installed with the flow in the wrong direction?


Yup check that. If that doesn't do it you can get a fuel pressure tester and check it at the rail. I forget the number but without a certain PSI it's not going to light off. Weak fuel pumps often behave this way . You'll likely find that it runs fine after it catches up........for now.
GM fuel pumps are about as crappy as they come . A 98 is ancient so chances are it's on pump #2 now. Also being ancient you should carefully check the fuel lines along the frame for wet spots, dark spots ect. That can cause your problems too. If you need those Rock Auto is the cheapest place I know of for high Quality FI lines. I put a set of those on a friends 03 las summer and was impressed.
If you have to do the pump and no lift it's easier to pull the box. Still a pain but easy repairs after it's off and only a handful of bolts. Air gun is your friend here! If you do pull the box check out the gas tank straps and frame rails while you're there. Neither of these are prizes either, I know I've got one...•
 
It takes 5 mins to hook up a fuel pressure gauge on this vehicle since it has a test port under the hood. Fuel pressure should not bleed off, and it should be a solid 60psi. either of those not right and either the fuel pump is bad or there is a problem with the fuel injector spider/pressure regulator assembly. I've done several Microgard fuel filters on these Vortec engines and never had a problem. That said, it could, in theory, be defective. Try to put your old filter back maybe? That said I've worked for the company that sells Microgard fuel filters for 2+ years now and NEVER seen a bad one come back as defective.
 
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Originally Posted by Ursatdx
Is it possible the FF was installed with the flow in the wrong direction?

Nope, I triple checked. Twice before tightening the lines on, once before firing it up. But good thought!

I'll try checking the ground at the tail light. Would have never thought to look there.

Air being sucked into the filter is also something I wouldn't have thought of. Would that cause these symptoms?

I'll also try testing fuel pressure and possibly start to suspect the pump. Thanks!
 
Well, turns out it was leaking from the "in" connection on the filter. Tried disconnecting and re-tightening. Still leaked. So I disconnected both ends to swap it for another filter. When I did, I found the problem. There is a tiny o-ring that got crushed on the fuel line on the "in" side of the filter. Swapped the filter and purchased a generic o-ring that was similar to the original. Voila! No more leaks, no more smells, no more cranking issues. All is well.
 
Glad you found it! I appreciate this post as I will be doing the fuel filter on my 93 1500 sometime in the near future and will be quite cognizant of this now.
 
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