Fuel Issue?

[FinnishDog]

1985 GTS cranks but wont turn over. Had this issue when we got the car, replaced the fuel pump and it ran fine until a week ago when it just died on the road. When jumping the yellow "T" connector by the air intake, we can hear the pump running. That led us to believe the COR was bad. Took off the relay, jumped B and Fp, and the car turns over and runs for a second before dying. I ordered another COR off Ebay and plugged it in. Its a gray plug opposed to the original yellow, which I think just means its from a 4runner or Pickup. Even with the new COR the car wont start. I'm a bit stumped now as to what the problem could be. Any help appreciated. Thanks!

[sirdan]

I think if the ignition system  sort of works like the COR. When I did megasquirt years ago I did not have the ignition stuff wired correctly so nothing from the computer was controlling it. The car would start and run for a second and die. I think you might have ignition issues. You could hook up a spark tester and watch if it loses spark then dies. The 85 is a different ignition than 82-84. I believe they call it the VAST or something along those lines. Hope this helps.

[FinnishDog]

Spark test showed good spark, it could still be ignition issues, I just don't have the knowledge to go through that right now. We disconnected the fuel lines at the pump/filter/cold start to see if fuel was moving and we got spray at every location. Our next thought is injectors but its not likely that all injectors failed right?

[blockade-runner85]

maybe so? was your tank gross when you switched fuel pumps? that or maybe fuel pressure dampener failure? possibly bad timing even, as ive seen perfectly healthy engines with garbage timing barely sputter up. also inspect the connectors to injectors, those are known to be really brittle over the years.

[FinnishDog]

Tank was pretty clean when we switched pumps. No rust but the old fuel pump filter was completely disintegrated. We got the particles out as best we could. Will be taking off the IM this weekend when I have more time and inspecting the injectors and surrounding area before committing to buying a new set. Will also run another fuel pressure test and check the timing while we're in there, and report back.

[danf]

It might help to understand how the fuel system works a bit to troubleshoot this one as I had the same problem.

The fuel pump is controlled by the AFM.

However, when cranking the engine (key in START position) the AFM fuel feed is bypassed to facilitate faster starts. The COR has two relay triggers that allow this. So when the engine starts (and you release the key to the ON position) the AFM has to provide power to the fuel pump circuit to stay running.

If you car starts, then stalls a few seconds later after releasing the key, I would be checking both the AFM (do this first - remove the air filter and push the air flapper door open with your finger and have someone listen for the fuel pump.) If nothing, then check the COR.

I don't have the pinouts handy but the AFM should provide power to a pin at the COR - you'll have to check the circuit integrity with a multimeter.

[ozzie]

Did you replace the inline fuel filter (the one on the side of the block) when you replaced the pump?

[FinnishDog]

Danf, thanks for the info. I'll do more digging into that topic.

Ozzie, yes we did replace the fuel filter when we changed the pump. Hopefully neither of them failed since they're so new (<2 months)

[FinnishDog]

We dropped the tank and pulled the pump and turns out... the hose for the pump inside the tank had somehow kinked and tore, causing a loss of pressure. Replaced the hose and the car runs again. Thank you everyone for the input, glad the people on this forum are extremely helpful!

[danf]

Make sure you use the correct type of hose in the tank. Standard fuel lines are not meant to be completely submersed in fuel and will fall apart! The hoses designed for in tanks are way more expensive than standard fuel line.

[FinnishDog]

Uh Oh. My dad is the one who went to autozone to pick up the hose. He said he got fuel injection hose (https://www.autozone.com/plumbing-hosing/rubber-hose/p/continental-5-16in-fuel-injector-hose-sold-per-foot/240844_0_0) and installed it already. I don't this this is the right kind of hose then.

[danf]

No, that looks like regular fuel line.

The problem is they don't treat the outside of the line for exposure to fuel. So it rots away and can get into the fuel pickup strainer and fuel filter.

O'Reilly's seems to have it: https://www.oreillyauto.com/detail/c/gates/gates-5-16-inch-i-d-fluoroelastomer-fkm-fuel-hose/gat0/27093

It says specifically it can be submersed in fuel, and it's usually way more expensive than normal fuel line. Around here fuel line is $1-2 a foot, and the submersible line was like $15 a foot. 

I don't remember what diameter it is in the fuel tank just make sure it says it's submersible when you get it. If they tell you all fuel lines are the same, they are incorrect.