scott90

1990 toyota extra cab 4wd with a 98 5vzfe in it. Can't find anything on here but something I noticed is that everytime I fill my truck all the way up it takes a few try's cranking it for about 5 seconds before it will fire up. Truck runs good after it fires up. Other symptoms are bad throttle response on acceleration from a stop. Sometimes coming to a stop on the highway doing about 60+ the truck will die or it will idle as if it has a huge cam("lopes"). Replaced maf,both o2s,coolant temp sensor. All other sensors test good. Leaning towards a fuel pump going bad. Also the truck takes a long time to warm up and when it does most of the time the lower radiator hose still feels cold. It doesn't overheat and the heater blows hot. Any ideas?

vasinvictor

iTrader: (3)

Who did that swap? Who wired it? How long have you had it?

scott90

I did the swap and I had the harness built by toy only swaps so it was plug and play. Had the truck for 3 years and it's been swapped for 6 months. Never did this before the swap.

scott90

need some help here guys don't wanna spend 130 for a fuel pump if there's something I overlooked

ZUK

iTrader: (1)

Maybe a stuck wide open thermostat.?

scott90

I was thinking that could be one of the issues, I just put the thermostat in maybe 4 months ago. Something else I've noticed is that the throttle response only goes to hell when it's warm and when it does if I shut the truck off and restart it,it goes back to normal for a undetermined amount of time

vasinvictor

iTrader: (3)

It's definitely a sensor. Its running ok in open loop, but once it goes closed it malfunctions. Get a live reader on it and see what sensors are offline or reading out of norm. Still could be a wiring issue, actual people make those harnesses.

Do you have the proper year maf and all other accessories for your ecu?

scott90

So far I replaced the maf,both o2 sensors,ect sensor, cam pos sensor,cleaned the iac,cleaned the tb,tested the tps, alt,new battery. All sensors came from the donor rig so they should be all correct. It just stumps me that I can shut the truck off and start it back up and the throttle response is fine.

Sdsupra760

Are you replacing parts with factory parts or autozone parts cuz you could just be chasng your tail. Sounds like it isnt running right and the fuel injection is getting conflicting signals. Swaps always have issues more often than not. Good luck. Coolant temp wiring and signals have to be spot on as well as maf and 02 and iat. I dont mess with swaps or buy vehicles with swaps or conversions for this very reason. Good luck

Sdsupra760

Also make sure its not just your isc valve

scott90

All parts were factory except the cts. Wiring shouldn't be an issue I never messed with the engine harness. And if a wire was crossed I would think it would run worse then it does. the isc valve? Do you mean iac? I cleaned and tested that already and it came back good. Also tested all the coil packs and they came back good as well. As well as the crank position sensor.

scott90

im mainly wondering if the hesitation could be related to the reason it's so hard to start after I fill the truck full of gas. Anyone know if this could be related and what usually causes this?

Sdsupra760

Check your evap purge line and purge valve. Sometimes if your purge valve is hanging open as you fill up your gas tank all that "air" or burnable fuel vapor gets pushed into the intake manifold and will kinda flood your motor with excess fuel. Then you have to crank and crank until it will finally start up. Thats the only thing i can think of that would be related to filling up gas. And this senario does happen. If you dont have a purge line hooked up well then....🤔

scott90

I'll check everything out when I get off work tonight. I kinda figured it would've been a bad fuel pump but that definitley makes sense. If the two vac lines that come from the pass side of the truck were backwards might do that too right? I think ones a fuel return and the other goes to the evap?

Sdsupra760

I really dont think its a fuel pump at all. Those usually quit working all together or when they do act up you will mash on the gas and the car will go no where and you will be like wtf lol. Like not even 10mph. You will know it is starving for fuel. Will be dramatic. The loping you describe reminds me of a stuck open purge valve. Definitly check all your hose routing in your evap system and make sure it is squared away. You may also have plugged evap vent hose or valve too so be thorough.

vasinvictor

iTrader: (3)

Good idea here. I deleted my evap stuff on my swap so I can't help you diagnose it. Check the 3.4 swap section for proper routing.

scott90

Ok thanks guys I'll check everything out this weekend and see what I can come up with. One more thing tho,the throttle hesitation when accelerating from a stop. It will go away for a undetermined amount of time if I shut the truck off and restart it. Ever heard of this before?

scott90

i checked the routing of the evap and everything looks good. Checked the purge line and unplugged it from the intake and the truck almost dies so Im guessing the valve is good. Checked the other hose coming from the valve and it didn't effect anything but the vacuum from that hose kinda had a thumping sound.

ZUK

iTrader: (1)

Scott,
I have a feeling it will be more obvious where the problem area is when you check your engine codes using the odb2 port. I bet you have 3 or 4 codes at least.

scott90

Only one that comes back is for the cam position sensor and speed sensor the rest or codes from running a auto ecu. Replaced cam sensor already no change