suntzumd

Ok - 85 gsl-se, runs great.

Recently when I stop after properly warming up and come back in say 20 to 30 minutes it won't start. Seems to me I've still got good compression as I've tried the complicated flood cure and pulled the plugs etc and gotten good blow off through the spark plug hole - however - the flood fix didn't fix it. So maybe it's not flooding like I first thought - it also doesn't blow any smoke either when it starts cold or after having trouble.

Only letting it set for a good amount of time and cooling off seems to cure it. Then it fire's right up and run's like a scalded dog.

So what's the deal? I think I've got good spark and good compression - no hessitation or anything when it's running. Any ideas?

THanks

ioTus

iTrader: (5)

You tried disconnecting the ground of the front coil and cranking it?

suntzumd

Yes I tried that as part of the deflooding procedure. Couls this be vapor lock or some kind of intermittant trouble with the fuel pump?

gump

i'm right there with you on this one. something about the hot start that is giving it a problem. I've lived with it for a few months now. I am able to get it started though when it happens by pushing the gas pedal down a little bit while it's cranking. leads me to believe i may need to make an adjustment to the throttle body.

FJ

sentzumd: when you pulled the plugs to try and unflood, were they dry?

The fuel pressure regulator supplies a higher pressure during hot starts to prevent vapor lock.
Normally, the vacuum line to the FPR has vacuum applied through a solenoid and the fuel pressure should be ~28 psi. When the intake air temperature sensor shows intake air above 122* F, the ECU cuts the 12v to the solenoid during cranking and for 60 seconds after starting. The FPR vacuum line is now vented and the fuel pressure should be ~37 psi.

If the vac line to and from the solenoid were leaking, you would always have the high pressure so that's not likely the problem.

The best bet is to check with a fuel pressure gauge, to be sure the regulator itself is good, but checking the sensor and vacuum from the solenoid is a start.

If the intake temp sensor (on the DC, just below the BAC) was bad and not showing that the engine was hot, you will not have the higher pressure. It's resistance should be:
41 (+/- 4) kohms @ 68*F
11.8 (+/- 1) kohms @ 122*F
3.5 (+/- 0.3) kohms @ 185*F
To check the vacuum: with a hot engine, disconnect the vacuum line on the engine side of the second solenoid from the front, on the solenoid rack. (Might want to loosen the hose a bit while the engine is cold.) Have someone start the engine and place your finger over the open stem on the solenoid. You shouldn't feel any vacuum. After 60 sec, it should suck air in.

The next source of starting problems that I would check , if you have fuel and spark and good compression, is the water thermo sensor (on the water pump housing). It affects the mixture more than anything else, I believe. Although I would think it would affect more than just hot starts if it was bad, it would be worth checking if the intake air temp sensor looks good. It's resistance should be:
16 (+/- 1.6) kohms @ -4* F
2.5 (+/- .2) kohms @ 68* F
0.3 (+/- .3) kohms @ 176* F

It would be a good idea to check the compression with a regular gauge. It's not as accurate as the Mazda version, but will give you a good idea whether compression is the problem or not. It's been said that the compression is lower on a hot engine, although mine was the same hot or cold (using a regular gauge). Maybe it's lower when hot with a bad corner seal or something similar.

Dirty fuel injectors, in my experience, cause flooding after the car has been sitting at least overnight. But I've seen it mentioned on the 2nd gen forum that it can also cause hot start problems. Maybe a bottle of injector cleaner would do the trick; or pull them if it's been many years without cleaning? When mine were dirty, it would flood and refuse to start only after sitting for hours; I never had a problem with hot starts at the time. Maybe they sometimes leak only when warm? If your plugs were dry though, I wouldn't suspect the injectors.

I don't really see vacuum leaks as the cause, as you haven't mentioned idle or other problems but it might be a good idea to check it. You should have a stable 18 to 20 in Hg at idle.

Just a couple of ideas. Good luck.

Gump: I don't know why opening the throttle helps, but I can't think of any adjustment on the throttle body that would affect hot starts. Maybe opening the throttle and allowing more fuel/air to flow clears the aeration if it is vapor lock? Might be, if it's minor. If it is slightly leaking injectors, the extra air would be what's helping to clear the excess fuel.

-John.

Guackman

I have the same problem. Drive for 20 or 30 min. Runs great. Idle is fine at stops, etc...

Stop and shut the car off for less than an hour or 2 and it starts, but then does not idle. It dies right away. I can hold the throttle a little to keep it going and then after a couple of minutes of driving, the idle is stable again.

Really strange. I'll have to digest the last post and see if any of this applies to me.

One thing I did notice on my car though (maybe it relates to the water thermo mentioned in the last post) is that my car temp never runs very hot. It stays just above the first line after the 40 on the water temp guage. Mine is in celcius I guess. Goes from 40 to 120 on the guage with 3 lines in between.

What is the normal temperature of the water? Shouldn't it be like 70 degrees celcius or so?

Thanks.

Greg
1985 GSL-SE.

Manntis

remember, the car has a sensor to detect water temp and set idle accordingly. When the car is cold, it'll idle at 2,000 RPM or so. As it warms up to op temp the idle drops to 900 RPM.

If the sensor (really a wax pellet) is screwy there's a chance it might think the car is at 2,000 when cold, when it's really at 900. So when it's warm the sensor thinks the idle is at 900, when the throttle is held so low as to let the car die at a 300 prm idle or some such thing.

It's important to remember that an engine is at it's hottest about 20 minutes after you shut it off - with no radiator-cold coolant flowing through it, the heat builds up. Then for the next while after the engine cools down. If you jump in and drive a car 1/2 hour after parking it, the engine really has just begun to cool.

suntzumd

Wow - lot's to digest and it's too late at night for that right now. However - I did forget that occasionaly I have this high idle variation. It's nice and steady but will idle at about 1.5k instead of the spec 800. Will check the things mentioned this weekend. I think a fuel pressure guage would be a great idea.

Let you know how it goes.

rotarygod

iTrader: (1)

My GSL-SE does the same thing. It is from the injectors being old and a little leaky. After you shut the car off, some of the remaining fuel pressure forces fuel through the leaky injectors and into the engine making it hard to start. Mine is actually fairly bad about this. To start the car I just reach down and pull out the fuse while I crank it. After a few seconds I reinsert the fuse and it starts every time. The fuse I pull is the 2nd one down from the top right corner in the fuse panel under the dash. I fiqured it out because my 2nd gen used to do the same thing. Try that and see if it helps. My idle is also fairly erradic. Sometimes it settles in at around 800 or so but then other times itsits over a thousand and jumps around. It gets annoying but its only my play car anyways.

Guackman

Manntis, Is the wax pellet sensor your talking about just the fast idle adjust thing. I notice that when the car warms up this rod comes up out of it's shell. It push another rod that when it is warm will disengage the fast idle. That's why they say to press the throttle down once before starting the car. Because it resets this lever so that the fast idle cam and this wax actuated rod can do it's job.

I am correct in my assumptions? or is their another sensor I should check.

One more small thing that might pinpoint my problem more specifically is that when I drive and then park the car, if I leave it for 5 or 10 minutes, then no problem with the idle. Maybe just a little rough at first, but if I leave it for 30 to 45 minutes it will not idle properly without me pressing the accelator pedal. Leave it for 2 or 3 hours though and it's no problem. It's also quite cold here in Montreal still and I seem to remember that when the temperature was warmer last fall and summer, it seemed to be more of a problem.

Anyway, no tinkering will happen this weekend. We're supposed to get 20 cms of snow!!!! I'll have to wait another week before playing around with all this great info.

Ciao for now.
Greg
1985 GSL-SE

FJ

Yours may well be related to the previously mentioned items as it occurs when starting hot, but as it starts fine it seems to me it may just be something simple. I.E., a dirty BAC that takes a moment to settle down after restarting. Your symptoms are rather mild, compared to the others.
Maybe some basic maintenance would solve your problem, if you have not already done so. To me, the first step with any idle problem is to clean the throttle valves and clean and lubricate the throttle shaft, then set the TPS.
If that doesn't solve it then you could clean at the BAC.


It's off topic, but my water temp gauge stays about a needles width below the "*C" writing at the top of the gauge; say about 4/10th of full scale. You probably have a bad sender, or the gauge itself.
It's not related to the water thermo sensor I referred to above. That one is a sensor for the ECU which it uses to set the mixture and therefore idle speed, etc; the gauge uses a sender which is located to the left of the oil pressure sender below, the oil filter. One wire on it. You can check the gauge by disconnecting the lead on the sender and connecting a resistor between the lead and ground, then turning the ign switch to on. A 104 ohm resistor should point the needle to the first mark. 21 ohms should point to the mark before "H" and 16 ohms would point to "H". That's according to the manual; I haven't tried it and can't at the moment as my harnesses are not connected. The closest standard value resistors you are likely to find are 100, 22, and 15 ohms.
If that checks out ok, then the sender is bad.

-John.

FJ

The high idle may be related to the hot start problem, but it's probably just the usual -SE idle antics. If you haven't done so lately, I would do as I mentioned in the previous post: clean the throttle valves, clean and lubricate the throttle shaft and set the TPS. Then clean the BAC if it still does it.
A vacuum leak would cause the same thing, but as it's intermittent it's not likely the case. You may want to spray carb cleaner or starter fluid around the intake gaskets and the large hose at both ends of the hard line going to the brake booster and see if the idle changes, just to check. If you can rotate the large hoses easily by hand, it's time to replace them anyway.

-John.

Rex4Life

You guys up there in Canada ought to be lucky your car starts at all in that kind of cold.

Scott

p.s. I used to live in Chicago so I know a little cold and remember how hard it is on cars.

Manntis

mine starts with no probs in -40, but I wouldn't drive it on the icy roads in that climate. I just started it sporadically throughout the winter and moved her fwd/back a few feet to keep things from seizing.

Markjg

Had a similar problem with my 85 GSL-SE. Tried all the suggestions I found here with little luck. Finally I sprayed the ignitor contacts and the harness plugs with Corrosion X cleaner/lubricator. Seems to have solved the starting problem so far.