4runner wont start when warm. No codes

[troyboy162]

ran into a problem at the hammers this weekend. The truck will not start after its warm. It cranks strong and fires a little sometimes, but wont catch. Let the truck sit for 30-40 minutes and it starts perfectly fine. No codes, no issues after it starts and no performance problems. I am thinking low preasure from the fuel pump at this point.

the good:
-truck runs fine
-idles fine
-no codes
-no sputtering or performance issues at any RPM
-will start back up if cranked right after turn off
-Can hear the fuel pump running when key is turned to start

the bad:
-If truck sits for ~10 minutes it will crank but not start
-May sputter a few times but will not start
-needs to sit for 30-40 minutes and then it will miraculously start like nothing happened.


done so far:
-cleaned IAC (idle air control) and it looks to be functioning perfectly.
-cleaned MAF and IAT (intake air temp)
-cleaned intake tubes and throttle body (dirty after the roll over)
-measured IAT vs actual intake temp and it looks to be off by 10 deg F...not too bad.
-have had luck spraying Maf cleaner past the MAF and trying to start. It will stumble a bit and then find idle with no further issues.
-replaced fuel filter

Since all my sensors appear to be doing there job. I am wondering if my junkyard fuel pump is just not up to spec on pressure. I have read that starts are picky about fuel pressure. Kind of a pricey part to throw at it but the pump is a junk yard unit and was exposed to bad times during my boiling fuel/vapor lock incident.

[paddlenbike]

I was going to suggest the fuel pump or possibly even the fuel filter. I just put a Walbro in mine this weekend, which is far cheaper than a Denso pump and it supports supercharging later if you ever go that route. There are some small modifications required to get the larger pump to fit, but it's no big deal.

[Seanz0rz]

after hearing that fuel pump whine, i'd start with that. I really think that is something you should be replacing anyway, because a dead fuel pump will completely strand you in the desert.

from there, it sounds like it is "overheating". Every time I come across these symptoms it is because the vehicle is hot and must cool down before the engine will restart. I'm not exactly sure what that means for you, but it may be a place to start.

[troyboy162]

yeah its heat soak of some sort. At first I believed it was a sensor that was heat soaking and malfunctioning, but I can see the readings coming from the MAF, IAT, and TPS. all are working normaly. I cant see the IAC feedback, but I cleaned it and thats really just controling idle speed and again no codes are being thrown.

now I think its just some preasure issue with the pump. Some preasure change must occure after sitting for a bit that the pump cant cut it until things normalize. I'll try to buy a fuel preasure guage, but if they dont have them I wont feel horible about replacing that fuel pump regardless of if it fixes it or not. I tend to think it will though.

[paddlenbike]

How long ago did you mess with the fuel pump? I would start dropping the front of the tank and checking the seal that goes around the fuel pump/sender unit. You might be able to reach it from the inspection cover under the rear passenger seat if you drop the tank a bit.

[Seanz0rz]

ken, troy has a f150 tank, so it's going to be a different beast.

[troyboy162]

yup it makes me uneasy having a ford part, but its been good so far. Seems that all cars can have these same symptoms but ushually have a assosiated CEL code to go with it. I have seen ford guys narrow onto the pump in a similar situation as mine, and also a 99 SC 4runner had the same. Oh well I'll find out soon enough.

[troyboy162]

ran into a snag and broke the vapor valve at the top of the tank. its a little gizmo that allow the tank to vent into the charcoal canister. $57 part avalible only from ford....lovely. Also ford has you crimp in new fuel pumps...thats pretty ghetto but I soppose it works fine.
If all goes well I should know by late tonight if the pump fixes the issue. Finger are all crossed

[paddlenbike]

Also ford has you crimp in new fuel pumps...thats pretty ghetto but I soppose it works fine.



When I installed the Walbro fuel pump (part of the URD kit), wire crimps are included and recommended for use. I crimped on the new fuel pump wiring and started to put it all back together when I got an uneasy feeling about the crimping. When I went to solder the connections I couldn't get the wires out of the crimp, so I guess it should hold.

The reason they have you crimp them is because most shrink-wrap is not rated to be submersed in gasoline.

[troyboy162]

pump looks to have fixed it. I tested the warm start issue twice and it worked where previously it was 100% failure. Should be fully trustworthy by tomorrow

[Crinale]

yay, good to hear Troy :thumbup:

[paddlenbike]

sweet.

[Seanz0rz]

glad you got it figured out!