Long Crank Before Starting When Warm (1 Viewer)

[702FZJ80]

My 96 does this as well. When cold, it fires up on the 4th or 5th rotation. When hot, it takes about double that, maybe 8-9 rotations before it fires up but once running it's fine. The only thing I noticed is that once warmed up and I put it in neutral, it idles fine but feels like it misses every so often. Instead of a glass smooth purrr, I get more of a purrrrRRrrrrrrRrrrrrrrrrrrRrrrr haha.

Do you have the CEL on? Have you taken any steps to try and remedy it? How long has it been doing it? If it's a matter of keep throwing parts at it, I'll probably just give up at some point, but I'm concerned about a sudden complete failure if that may be imminent.

 

[Onefastrx7turbo]

No CEL's and haven't changed any parts yet. I can say that the fuel tank always has pressure in it when I gas up. I guess I could try releasing the fuel pressure the next time I hot start it to see if that makes a difference.

 

[702FZJ80]

Interesting, same here with the pressure in the tank.

I'm considering replacing the charcoal in the canister and blowing out the check valves with lots of carb cleaner and compressed air per a thread here. If the tank is building too much pressure it makes sense that either the check valve from the tank to the charcoal canister is blocked, or there is a restriction inside of the canister itself.

 

[702FZJ80]

So I refurbished the stock charcoal canister with fresh charcoal and cleaned up the check valves.

The truck was running great for about 8 miles and was restarting well too. Great I thought, time to disconnect the battery to clear the cel and call this done. As soon as I went to start it it cranked long and had no power at all. I got it home by flooring it and above 3k rpm it made decent power. Gas tank pressure built up really high when I checked and now code

P0125

It seems the computer thinks temp is too low for closed loop. I noticed the other day when all this started the temp gauge dropped to like the 1/4 position for no reason.

Which sensor is the one that talks to the computer? It seems there are a few of them.

And would that sensor cause the truck to run so poorly intermittently?

Thank you!

 

[Onefastrx7turbo]

UPDATE: I released the pressure today and hot started the truck with no effect on cranking time; was still longer than cold.

 

[702FZJ80]

New Fuel Filter with lots of black gunk that came out, no change in performance, still runs like doo-doo.

 

[702FZJ80]

FIXED!

I checked the fuel pressure at the banjo bolt on the tank and was getting 20PSI at idle and it wouldn't go up when running the RPM's up. As soon as the key was shut off, the pressure dropped instantly.

The cause?

The pump itself worked itself out of the housing and was hanging crooked off the side of the housing and the hose was only about half way on. Letting most pressure blow by obviously. Put it all back together, bending the little mounting bracket at the bottom up a bit at the ends to hopefully hold it better. I was going to put a piece of stainless steel wire tie around the pump to the pump body but was worried about grounding the pump out so I didn't . If this problem happens again I'll probably buy a submersible fuel tank hose ($30 per foot at Napa) and line it with wire to keep from grounding out the pump and put it around the pump and secure it to the housing. For now, I think it will be great.

Thanks for everyone's insight and tips! I really got to know the truck along the way and have done plugs, fuel filter, new vacuum lines, rebuilt charcoal canister, cleaned out EGR, cleaned contacts on Fuel Relay and new tape around the wiring harness near the MAF etc etc etc. So lots of PM done anyway.

If your truck doesn't want to run, CHECK YOUR FUEL PRESSURE!

 

[Onefastrx7turbo]

Good insight. FWIW, the fuel pump and sender are grounded inside the tank, so you could have secured the pump to the hangar but unless it was insulated, you might have had some additional noise from the fuel pump vibrations.

 

[Jorgito]

FIXED!

I checked the fuel pressure at the banjo bolt on the tank and was getting 20PSI at idle and it wouldn't go up when running the RPM's up. As soon as the key was shut off, the pressure dropped instantly.

The cause?

The pump itself worked itself out of the housing and was hanging crooked off the side of the housing and the hose was only about half way on. Letting most pressure blow by obviously. Put it all back together, bending the little mounting bracket at the bottom up a bit at the ends to hopefully hold it better. I was going to put a piece of stainless steel wire tie around the pump to the pump body but was worried about grounding the pump out so I didn't . If this problem happens again I'll probably buy a submersible fuel tank hose ($30 per foot at Napa) and line it with wire to keep from grounding out the pump and put it around the pump and secure it to the housing. For now, I think it will be great.

Thanks for everyone's insight and tips! I really got to know the truck along the way and have done plugs, fuel filter, new vacuum lines, rebuilt charcoal canister, cleaned out EGR, cleaned contacts on Fuel Relay and new tape around the wiring harness near the MAF etc etc etc. So lots of PM done anyway.

If your truck doesn't want to run, CHECK YOUR FUEL PRESSURE!

Hi,

what issue was solved by this ? The long cranking when warm or poorly running engine ?

Thanks,

Jorge

 

[702FZJ80]

Hi,

what issue was solved by this ? The long cranking when warm or poorly running engine ?

Thanks,

Jorge

Sorry for the delayed reply........

The engine ran like a top afterward but still long cranked when hot outside. I think it's just the nature of the beast with these things with how many people have that same issue.

 

[IdahoDoug]

So, has anyone figured out this long crank thing? Seems like it is the 95-97s that do it. Mine does as well and in the last 1000 miles I have replaced a bunch of parts for PM unrelated but I thought perhaps might fix it. Nope. Fuel pump, fuel filter, coil, EFI and the relay in the driver's kick panel (no volt relay?), plugs, plug wires, cap, rotor, fusible links, battery, starter contacts, air filter, fuel injectors professionally cleaned, timing confirmed, intake rubber tube intact. No impact at all. When I did the HG 160k ago, I also cleaned the intake, EGR, tried to fix the CEL by cleaning out the tiny intake air passages, etc. CEL has been on forever and I've always wondered if this kicks it into some mode for starting. Who knows? Anyhow, adding to the database. If anyone's figured this out, I'd love to know it. Thanks

 

[96LX]

I have the same exact issue with long cranking while the engine is warm and cannot figure this out. It takes so long everyone in the vehicle becomes concerned but it always eventually starts.

 

[Lextronix]

Try to test your fuel pressure VSV. I removed all of the VSVs(Pair, EGR, FP) under the intake plenum during my head gasket work. Started fine when cold but cranked for what felt like an abnormal amount of time after trying to restart in between errands/stops. I added the FP VSV back and it has consistently started within three or four turns.

This is the thread that helped me figure it out. Fuel Pressure VSV Delete - https://forum.ih8mud.com/threads/fuel-pressure-vsv-delete.1067127/page-3

 

[60wag]

I replaced the fuel pressure regulator on mine and that appeared to fix the delay in starting.

 

[awf]

Try to test your fuel pressure VSV. I removed all of the VSVs(Pair, EGR, FP) under the intake plenum during my head gasket work. Started fine when cold but cranked for what felt like an abnormal amount of time after trying to restart in between errands/stops. I added the FP VSV back and it has consistently started within three or four turns.

This is the thread that helped me figure it out. Fuel Pressure VSV Delete - https://forum.ih8mud.com/threads/fuel-pressure-vsv-delete.1067127/page-3

94 FZJ80 owner here grateful for the hundreds of tips that have gotten my rig to almost mechanically sound -- that and a fair bit of work at OTRAMM. I'm experiencing the "starts quickly when cold/takes long cranks to start when warmed up" issue. I'm on the verge of doing the VSV replacement w/o removing the plenum. Is the consensus that a bad VSV causes this issue? I see a few posts mention it, but many more discussing replacing the VSV to address a CEL. I have no CEL's (thanks in part to a long-term EGR test kit), so I'm not chasing another EGR issue -- just the slow to start problem.

 

[ColoradoBoy]

I replaced the fuel pressure regulator on mine

94 FZJ80 owner here grateful for the hundreds of tips that have gotten my rig to almost mechanically sound -- that and a fair bit of work at OTRAMM. I'm experiencing the "starts quickly when cold/takes long cranks to start when warmed up" issue. I'm on the verge of doing the VSV replacement w/o removing the plenum. Is the consensus that a bad VSV causes this issue? I see a few posts mention it, but many more discussing replacing the VSV to address a CEL. I have no CEL's (thanks in part to a long-term EGR test kit), so I'm not chasing another EGR issue -- just the slow to start problem.

FPR is a good thing to check for this, as 60wag says. Was my issue awhile back. Granted, I have a 3-FE, but same symptoms. Ended up replacing my fuel pump and also installing a new FPR fixed it. Bought a cheap Harbor Freight pressure test kit- made it much easier to track down the issue.

 

[awf]

FPR is a good thing to check for this, as 60wag says. Was my issue awhile back. Granted, I have a 3-FE, but same symptoms. Ended up replacing my fuel pump and also installing a new FPR fixed it. Bought a cheap Harbor Freight pressure test kit- made it much easier to track down the issue.

Thank you. I’ll head to harbor freight for the test kit. I’m there every few days as it is.

 

[awf]

For those struggling with the long crank when warm issue, I am posting simply to share the conclusion of my long search. In my particular case (’94 FZJ80), I worked through the entire fuel system (except for replacing the injectors — that was the very last thing on my list given the complexity of removing the plenum), until I found that a PO has installed the fuel pump in bizarre manner. When I opened the tank I found an after-market fuel pump zip-tied to the fuel pump assembly. I’m not sure if it was the angle at which it was attached, whether the check valve wasn’t working, or something else — I didn’t bother doing a long diagnostic. As soon as I saw it, I realized the odds were I’d found the source of my problems.
I would have found the issue sooner, but I waited 3 months hoping to be able to get the Denso 950-0109 fuel pump kit many on this site recommend to replace the OEM pump, etc. But that pump seems to be no longer made, or, at least, Denso has it on backorder with no expected availability date. So I went with the Delphi FE0402 and matching fuel sock FS 0088. The fuel pump doesn’t come with the rubber pad that goes under the pump, so I was fortunate the PO had replaced that, and the one in the tank was reasonably new. Also, the Delphi sock is smaller than the OEM sock. But, the Delphi pump and sock work well, and my long crank when warm issue is finally gone. Whew.