car wont start when hot

[carfanatic89]

Hey guys, im new to the forum. Hopefully yall can steer me in the right direction. I have a 87 mkiii with a JDM 7mge with about 45,000 miles and Im having some problems. It kinda sounds like a ecu problem, but I need more input from other ppl.

Ive been dealing with this problem for the last year or so, so im ready to fix her. My car will not start when hot. Its hard to start when cold. It takes about 3 times to start. But when it gets warm after going to the store, when I go out to start it after sitting about 20 to 30 mins. It will not start. It will rev to about 1500 rpms then dies and I have to wait till it cool again to start it. It runs fine when hot, but after sitting for about 20 mins it will not start.
If I get it to start it will run like crap for about 4 miles then clears out.

Here a list of the things I checked and the new parts on it. Checked the TPS, MAF sensor, Air intake temp sensor, cold start injector timer switch and checked fuel pressure. Its at about 25 psi. I also checked the coolant sensor, and the pickup coils in the distrubutor. I replaced the FP relay, fuel pump, fuel filter, cap, rotor, wires, plugs, tps, o2 sensor, and air filter. I dont know whats wrong, but hopefully I can fix her. Let me know what you think. Im running out of parts to replace. thanks for the input. sorry the post is so long.

 

[Nomad707]

how are your injectors? sounds like one or two or more may be sticking. you can take them out easily and have them flow tested and or cleaned.
Check your codes, it most likely WILL throw an engine code when its running that shitty..

 

[MDCmotorsports]

how are your injectors? sounds like one or two or more may be sticking. you can take them out easily and have them flow tested and or cleaned.
Check your codes, it most likely WILL throw an engine code when its running that shitty..

Rubbish.

FPU = Fuel Pressure Up
VSV = Vacuum Solenoid Valve
FPR = Fuel Pressure Regulator

Start with looking at your FPU VSV for the FPR.

Check your vacuum lines going to and from the VSV and the FPR.

Check that the harness, clips, or pins are not missing/broken/corroded on the VSV.

Check that your cold start injector and cold start injector water temp sensor are both working and that the harness is in good order.

Then, and only then, move on to what the other guy said.

 

[carfanatic89]

When I look for ECU codes it tells me Vehicle speed sensor(probably b/c my speedo guage dont work) and thats all it tells me is wrong with the car. I dont think that its the injectors sticking because I kept the guage on there for a week and taped it to the windshield and I retains pressure after the cars turned off for about 3 hours. As far as I know all the vsv's are working properly. I can take the vacuum line off the fuel pressure regulator and feel the vacuum and it losses vacuum when I rev the motor, it could be the FPR itself, but a new one is pretty expensive to just be guessing, but I have some more info that might help find the problem.

I finally got a timing gun and checked it. I warmed it up, and jumped the te1 and e1 terminals, and was Idling at 800 RPM. It read about 20 degrees BTDC, which is way out of spec. So I adjusted it to 10 BTDC like the book says, and now it runs even worse. 1000 to 3500 rpms is fine, but no full throttle and no power above 3500 RPM. If I do give it full throttle it missed really bad and wont even accelarate and above 3500 RPM it misses bad but will accelarate as long as I ease into full throttle. This doesnt make any sense, I put it where it needs to be and it runs worse than when its out of spec. Its a JDM motor, would that make a difference.

 

[AJ'S 88NA]

Have you checked the timing belt and made sure the marks line up per TSRM?

How old are your plug wires?

And the FP does seem a little low, maybe with in spec though.

 

[carfanatic89]

I just check the lines and they line up and the rotor is pointing to #1 and tried to re-time it and now it reading like it suppost to 10 DBTC. I just took another look at the book though and it say spec is 40 psi with no vacuum, 10 uder what I have but mabye thats just enough. Im gonna go get a walbro fuel pump along with some ngk plugs in about a week, I already have the NGk wires, Ill keep yall posted on what happens

 

[carfanatic89]

Well I recently found that my fuel pressure tester was stolen, I live on a college campus. I guess thats was I get for having the party apt. lol, but I did find something very interesting. I was searching online last night and a guy has some problems like mine and someone told him it might be a resitior in the ECU. Well for whatever reason I went out to my car to day, took out the computer and took a peek inside. On of the resistors is burned up. I have a pic here for yall.



I just have one question though. What now should I try to repair it, or should I go buy another ecu from ebay, or a salvage yard. I can also get a refurbished one but thats about 400 bucks, and I dont have that kinda money at the moment. What do yall think. Thanks

 

[mclabaugh]

did you ever fix you acceleration issue?? i am asking because i have something similar going on with it not accelerating above 3500 also..thanks,
mike.

 

[carfanatic89]

Nope, I got the ECU back from the computer store. I put it in and now it will not run. It will start, run for a few seconds then dies and wont start again for about 30 mins. and will do the same thing again. I dont know what to do. Its getting fuel, air and spark so I dont know what to do. Should I buy a used ECU from another supra? Maybe what burned up the resistor is whats causing the problem. Another thing when I brought it to the computer store they couldnt tell the ohm of the original resistor. All it had was a 3 R on it so they guessed it was a 3.6 ohm rating. If I post a better pic of the ECU will somebody open their ECU with the same part number and tell me the was the resistance of the resistor. I would greatly appreciate if someone would. The part number of the ECU is 89661-14091. I would ask somebody around where I live to do this, but I own the only supra in the area.

 

[hvyman]

it is really rare to find the ecu at fault. you should have tested it before taking it to a comp store and even at that i highly doubt they could work on it.

-do you have egr?
-see if you can swap ecus with some one near buy
-check spark plugs
-cold start injector
-injectors and wiring and resistor
-test idle speed control valve(isc)

 

[carfanatic89]

I did test the resistor. And I also found that it controls the FP. There was no continuity between the 2 sides of it. Im about to buy a used computer here in the next few weeks (moneys tight). The only way I can get my car to run is to jump the b+ and the Fp terminals on the diagnostic plug in. Which takes the computer out of the loop on controlling the fuel pump. I have to buy a new fuel pressure tester and a compression tester, both mine where stolen. once I do that im gonna replace the intake tube, because its old and has some stress cracks in it and might be letting unmetered air into the engine. After all that if its still not working I dont know what im gonna do. but hopefully some of these test tell me whats the problem. I keep yall posted on what happens.

 

[tsparks01]

it is really rare to find the ecu at fault. you should have tested it before taking it to a comp store and even at that i highly doubt they could work on it.

-do you have egr?
-see if you can swap ecus with some one near buy
-check spark plugs
-cold start injector
-injectors and wiring and resistor
-test idle speed control valve(isc)

chk ur sold start and hot start injector switch...cold, located on ur thermostate housing and ur hot start is located on the air intake manifold...

 

[carfanatic89]

Im sorry for the wait my comp crashed, I don't have an egr, plugs are fine, I checked the cold start injector and time switch, both are fine, I really think that its the ecu, just because it was fine one day and the next it was acting up and none of the sensors are messed up. I cant swap with anyone, I have the only supra for about 30 miles and I cant just walk up to someone in dallas and say hey can I use your cars ECU real quick, Ill be back in a min. lol I bought an ecu and its on the way, nothing under the hood is wrong with the car I went thought the manual and went page by page and checked everything that I could possibly be checked. Ill let yall know what happens when I put the new/used one in.

 

[Nick M]

Oh my....

 

[carfanatic89]

Alright guys i got my new computer in and she is running alot better, but it still kinda hard to start. I think i have low fuel pressure though, the car starts to cut out at about 3,200 rpm and anything over 1/4 throttle and it falls on its face. It starts cutting out and backfiring though the exhaust.

 

[AJ'S 88NA]

It sounds like timing, either cam timing or static timing, I think that's what it's called, timing it with a light and with the jumper wire.

 

[carfanatic89]

I've all ready set base timing, 10 BTDC is what the book says. but that dont matter know b/c i pulled the ign fuse in the fuse panel thinking it might have some crud on it and not allowing the fuel pump 12v, it look good so i put it back in and guess what now the damn car wont start and the fuel pump wont turn on at all. I think the supra gods hate me or something.

 

[carfanatic89]

Got it started again, im takin to my mechanic tomorrow :nono:. I really dont want to but I cant figure it out and there a really good mechanics shop so I know they will take care of my car. I keep yall posted on what happens.

 

[Zumtizzle]

Rubbish.

FPU = Fuel Pressure Up
VSV = Vacuum Solenoid Valve
FPR = Fuel Pressure Regulator

Start with looking at your FPU VSV for the FPR.

Check your vacuum lines going to and from the VSV and the FPR.

/Thread.

 

[MAC_raptor]

Well If you go over a 1/4 throttle and it falls on its face like that, you are most likely(from what Iv read of your problem) looking at a fuel preassure issue. Your arn't getting enough fuel to air and your car is leaning out pretty hard. I had another car that did the same thing. Maybee just stating the obviouse...