87 Turbo : >> HOt engine restart problems...

[suprasvoboda]

HI everyone

I have a nagging issue that is really puzzling me.. and i need someones help

Have an a 87 turbo that's Ive owned since new.. ( yes .. Im a true gear head!) with a difficult hot engine re-start problem ..... .

When i go to restart it after its run fvor 10 min or more....., i have to hold the throttle wide open so it doesn't stall out. If i don't hold the "petal to the metal," it will catch right away but coughs and sputters at 300-400 rpm and stalls out... in 2-4 seconds & will not start again ..........., until it cooled down enough or i hold the Throttle plate wide open till it catches and starts to build up speed . (Its much worse in the summer than in the winter down here in Texas... )

Of course the trick is to let off at 2000-3000 rpm so u don't go above that !!

Ive heard it can be the VSV under the intake manifold , or other vacuum issues. I have not replaced it mindlessly, as i want to make sure i get it RIGHT !! What are all the possibilities it can be for this issue and where or what are some links i can go to read and fix it !


It starts wonderfully on cool or cold days,, and anytime in the morning .

 

[Silver MK3]

I have the same problem but my car is N/A. I replaced that VSV under the manifold because mine had a slight crack in it but it did not solve my problem. I tested every sensor on the car and they all checked out. I even tried running ethanol free gas and this maybe helped marginally but not much and not for almost a dollar more a gallon. I basically narrowed it down to a check valve in the fuel pump that doesn't work correctly any more and therefore won't hold the pressure in the line. I believe that is correct, it's been a while since I messed with it on my car since I don't want to replace the fuel pump for just that. It is frustrating especially when its 100* outside and the car just does not want to stay running until you get the idle to come up.

I believe you can jump the fuel pump at the diagnostic box using a jumper cable. You can do that after the car has been sitting for 10-15 minutes and let the jumper in there for a minute or so and if the car starts up fine then the valve is most likely your problem.

 

[aljordan]

Try this. Rather than starting the car, turn the key to "on" for 3 seconds, then back to "acc". Perform this cycle 5 times allowing 3 seconds between each one. What this does is commands the fuel pump on to build pressure in the system. You will build pressure each time you perform this key cycle. Once you'd done this 5 times, start the car as you normally would. If the car starts without an issue, this is a "heat soak" (fuel turning to vapor in the fuel rail due to engine heat) concern. Not really an issue as toyota knew about it and put a VSV in to bump up the fuel pressure in order to combat this.

If the car still has an issue, attempt this key cycle 10 times. If you still have the issue, there is something else wrong and it is not heat soak. If the car starts normally after 5 cycles, next time try 4 and then 3. See if there is a sweet spot the car likes.

Good luck. I've had the same issues on my car when it had 15k miles. It's a minor annoyance.

 

[suprasvoboda]

thank u for the repsonse and help......... ill try it this weekend. I also check the VSV valve under the intake manifold.
as far as the fuel pump... thats located in teh tank... and that means a whole lotta work ..!! taking it down, then getting the FP out of it . i dont even know how to test the presure relief valve......
any links or info on where or how to do that> ??

kev

 

[supraguy@aol]

Replacing a fuel pump is a two hour job, provided the tank is nearly empty, and you don't break anything along the way.
Plus, it makes it easy to replace the fuel filter, which DOES get clogged.

 

[7M4EVR]

So that's what the inside looks like eh? But 2 hours, maybe for your perfectionist ass haha! Maybe the first time ever but my fuel pump changes are about 30min tops. Maybe cuz I've done it so many times between switching pumps and troubleshooting...the filter can be tricky if u got big hands but that's a 15-20 minute job even with the tank in.

Unclip the 2 connectors in the back hatch
Put back wheels up on jack stands
Drain tank or run it close to empty
Unbolt straps (4 bolts)
Put a jack underneath center of balance of tank
Loosen clamps and pull off the two fuel lines (be gentle here)
Unscrew gas cap
Lower jack down slow keeping tank steady (congrats just dropped the tank)
Unscrew the hanger screws and pull out hanger
Change pump
Now go in reverse and be amazed how easy it turned out to be lol hardest part is getting them damn straps bolted back up.Helps to have another guy there to balance tank and pull on the straps so u can get the bolts started. If ur by yourself use the jack and put your bolt through the strap, lay under it the car with your feet toward the rear and pull on the strap as try to get the bolt started

 

[Silver MK3]

Try this. Rather than starting the car, turn the key to "on" for 3 seconds, then back to "acc". Perform this cycle 5 times allowing 3 seconds between each one. What this does is commands the fuel pump on to build pressure in the system. You will build pressure each time you perform this key cycle. Once you'd done this 5 times, start the car as you normally would. If the car starts without an issue, this is a "heat soak" (fuel turning to vapor in the fuel rail due to engine heat) concern. Not really an issue as toyota knew about it and put a VSV in to bump up the fuel pressure in order to combat this.

If the car still has an issue, attempt this key cycle 10 times. If you still have the issue, there is something else wrong and it is not heat soak. If the car starts normally after 5 cycles, next time try 4 and then 3. See if there is a sweet spot the car likes.

Good luck. I've had the same issues on my car when it had 15k miles. It's a minor annoyance.

I don't think our cars turn on the fuel pump when the ignition is only switched to on, that's why you have to jump the two connectors in the diagnostic port. I'll try and pull up the old thread I made on this a few years back. There was more information on this there. It is a minor annoyance, but when someone complements you on the car and then when you go to start it it barely stays running or stalls you tend to feel a little dumb...

thank u for the repsonse and help......... ill try it this weekend. I also check the VSV valve under the intake manifold.
as far as the fuel pump... thats located in teh tank... and that means a whole lotta work ..!! taking it down, then getting the FP out of it . i dont even know how to test the presure relief valve......
any links or info on where or how to do that> ??

kev

That's the main reason I haven't replaced mine because the whole tank needs to be dropped and the whole fuel pump needs to be replaced. If it was something simpler I would have fixed it already on mine. The easiest way to test the valve is probably the way I mentioned in my previous post. If it starts fine everytime after jumping the fuel pump and it does this consistently then you can most likely assume it is your problem. I'm going to try and find my old thread on this and see what all was in there.

Replacing a fuel pump is a two hour job, provided the tank is nearly empty, and you don't break anything along the way.
Plus, it makes it easy to replace the fuel filter, which DOES get clogged.

That filter had definitely seen better days! I think my car had the fuel filter changed right before I got the car because it was super shiny and new looking, but if I do replace the fuel pump I would most likely replace the filter as well just for peace of mind.

So that's what the inside looks like eh? But 2 hours, maybe for your perfectionist ass haha! Maybe the first time ever but my fuel pump changes are about 30min tops. Maybe cuz I've done it so many times between switching pumps and troubleshooting...the filter can be tricky if u got big hands but that's a 15-20 minute job even with the tank in.

Unclip the 2 connectors in the back hatch
Put back wheels up on jack stands
Drain tank or run it close to empty
Unbolt straps (4 bolts)
Put a jack underneath center of balance of tank
Loosen clamps and pull off the two fuel lines (be gentle here)
Unscrew gas cap
Lower jack down slow keeping tank steady (congrats just dropped the tank)
Unscrew the hanger screws and pull out hanger
Change pump
Now go in reverse and be amazed how easy it turned out to be lol hardest part is getting them damn straps bolted back up.Helps to have another guy there to balance tank and pull on the straps so u can get the bolts started. If ur by yourself use the jack and put your bolt through the strap, lay under it the car with your feet toward the rear and pull on the strap as try to get the bolt started

I always thought that the fuel pump was a really complicated job, but you guys make it sound alot easier than I thought it would be. Maybe I need to once again confirm that this is my problem and go ahead and replace it if it is this simple.

 

[Silver MK3]

Here's my thread on the FPU VSV and there is information on the fuel pressure check valve in here also.
http://www.supramania.com/forums/showthread.php?156796-Fuel-Pressure-Up-VSV&highlight=start

I haven't found where I read that the car doesn't turn on the fuel pump when the ignition is only switched to ON, but I am pretty sure I read this. I'll try and find it.

 

[3p141592654]

Only three ways to get a turbo fuel pump to run:
1) key in start position (i.e. cranking)
2) Rotating engine
3) Jump FP terminal in check box.

I would check fuel rest pressure. If the pump check valve or regulator are leaking the pressure will drop and fuel with vaporize in the rail. The fuel pressure up system should be checked, but your symptoms seem far worse than what you would get with a bad FPU.

 

[Silver MK3]

Only three ways to get a turbo fuel pump to run:
1) key in start position (i.e. cranking)
2) Rotating engine
3) Jump FP terminal in check box.

That's what I thought.

Just out of curiosity do you know if this applies to the N/A 7M as well?

This thread has sparked my interest in solving my hot start issue as well. I think I am going to jump the fuel pump tomorrow and see if my car starts normally or not. If so I will look into replacing the fuel pump. It has given 27 years of good service, despite only having 89k on it.

 

[3p141592654]

#1 and #3 are same for NA. The NA has a switch in the Flapper AFM that turns on the pump if there is air flow detected.

 

[Silver MK3]

#1 and #3 are same for NA. The NA has a switch in the Flapper AFM that turns on the pump if there is air flow detected.

Thanks! That's what I was hoping for.


Suprasvoboda I just reread you initial post and saw that you said you are the original owner. Congrats! Not many of you left.

 

[supraguy@aol]

My car has a long initial crank time, but not just when it's hot. I suspect my cheap Ebay fuel pressure regulator, so I bought this to install this week.

 

[Silver MK3]

Just a note for the OP. I tested my fuel pump check valve using the jumper in the diagnostic box today. I let it sit in there for about three minutes and started the car with the jumper still in. The car started up great every-time with the jumper in and did not when the jumper was not it. I would definitely test this on your's as well. I just ordered a Denso OE fuel pump on Amazon for $87 so it isn't an expensive fix and doesn't sound like it will be too bad to replace the pump. I hope this fixes my problem and maybe your's as well. Good luck!

 

[jetjock]

^ Keep in mind there's more involved in holding rest pressure than the fuel pump check. Anything that leaks on the supply side (regulator back) of the fuel system can be responsible.

 

[Silver MK3]

^ Keep in mind there's more involved in holding rest pressure than the fuel pump check. Anything that leaks on the supply side (regulator back) of the fuel system can be responsible.

I didn't really think about that. What all is there from the regulator back that could leak?

I don't have an external leak where a hose or connection is leaking for sure, and I doubt that my injectors are leaking, they show no signs of it. The only things that I can think of are the regulator and maybe the damper, but I don't see how the damper could. The way I understand it is that when the car is shut off the regulator closes off the return line to the tank and then the check valve closes in the fuel pump to "trap" the pressure while the car is off. If so and there are no external leaks I would assume that the only reasons there would be a loss of rest pressure would be a bad check valve or regulator. Is there any way to tell which it is?

I would think that the check valve is the problem more times than the regulator, but I could be wrong.

 

[3p141592654]

First make sure there is no fuel in the vac line of the regulator. You can put a stethoscope on the regulator and sometimes hear the leak after pump off or pinch off the return line and see if the pressure holds. You can remove it and pressure test it on the bench as well. One or more dripping injectors will also bleed off pressure quickly. The pump is a PIA to change, so make sure it is not something else.

 

[Nick M]

I suspect my cheap...

I am not picking on you, I haven't seen a need for it. I just wanted to repeat this for millennials.

 

[suprasvoboda]

YEs, I know !!!
and there aren't many CARS still left!! in this category... They are now classified as COLLECTORS I think- !!

how do u "jump the FP" as they say in the blog... what terminals to I connect or how is this done..? any links or pictures would certainly help - ie TSRM illustration , ect

thank you
SUPRASVOBODA

 

[supraguy@aol]

In the diagnostic box next to the igniter, you'll see a diagram on the inside of it's cover; You want to jumper Fp and B+.