Co-workers 1990 Hard start when hot
Thread Starter
Pro
Joined: Nov 2009
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From: Maple Grove Minnesota
Co-workers 1990 Hard start when hot
A co-worker has a 1990 coupe. She says it starts just fine when cold but once it is warmed up she has to crank it 10-12 revolutions before it will start again then after it is running again she smells fuel (running rich).
She had it at a Goodyear store for an oil change and they told her it was the FPR. Does this sound like a likely cause? I hate to see her put $621 into it if it isn’t going to cure the problem. Thanks…
She had it at a Goodyear store for an oil change and they told her it was the FPR. Does this sound like a likely cause? I hate to see her put $621 into it if it isn’t going to cure the problem. Thanks…
Le Mans Master
Joined: Oct 2006
Posts: 6,842
Likes: 285
From: Palmdale CA
On the L98 TPI engine, the FPR or Fuel Pressure Regulator is often the cause of the hot start problem. $621 is pretty steep to replace one of those. I didn't want to do it (after putting the heads back on, I was sick of working on it night and day for weeks) and I believe my experienced mechanic did it without removing the intake plenum (I got him to admit it somewhat). If you look at the FPR the torx bolts are really small, but there's room to put a torx bit in the holes and loosen them with a small box end wrench.
The FPR is on the passenger side, on top of the engine and underneath the intake plenum. What happens is that a bad FPR lets the fuel flow back to the tank instead of holding it there at the fuel rails, for an instant start.
The FPR is on the passenger side, on top of the engine and underneath the intake plenum. What happens is that a bad FPR lets the fuel flow back to the tank instead of holding it there at the fuel rails, for an instant start.
Thread Starter
Pro
Joined: Nov 2009
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From: Maple Grove Minnesota
The FPR is on the passenger side, on top of the engine and underneath the intake plenum. What happens is that a bad FPR lets the fuel flow back to the tank instead of holding it there at the fuel rails, for an instant start.[/QUOTE]
Would this make it run rich once restarted?
Would this make it run rich once restarted?
Le Mans Master
Joined: Oct 2006
Posts: 6,842
Likes: 285
From: Palmdale CA
Race Director
Joined: Apr 2000
Posts: 15,344
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From: Texas
Classic symptoms of a bad Fuel Pressure Regulator. This is also the easiest thing to check....
- Follow the vacuum line from the FPR to the intake
- Pull the vacuum line off of the intake and check for fuel in the line
- If there is fuel present (or indications that fuel has run thru the line), the FPR is bad. If the vacuum line is 100% dry, the FPR is fine and it's time to look elsewhere.
To swap the FPR on an L98 takes less than an hour even if they pull the plenum. If the factory FPR is that expensive, I'd buy an aftermarket FPR for about $50. Combined with an hour of labor, it's a $150 repair vs $600+
- Follow the vacuum line from the FPR to the intake
- Pull the vacuum line off of the intake and check for fuel in the line
- If there is fuel present (or indications that fuel has run thru the line), the FPR is bad. If the vacuum line is 100% dry, the FPR is fine and it's time to look elsewhere.
To swap the FPR on an L98 takes less than an hour even if they pull the plenum. If the factory FPR is that expensive, I'd buy an aftermarket FPR for about $50. Combined with an hour of labor, it's a $150 repair vs $600+
Pro
Joined: Oct 2006
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From: Bryan Texas
Could be a bad injector too, I'm going through the same thing. I'm waiting on injectors froom FIC now, picked up a new fuel pressure regulator at autozone today. Going to change it all out in one foul swoop, shouldn't take more than a couple of hours.
In my experience injectors can leak through the electrical connection area. It's easy to ohm them out, should be 16ish or higher. A really bad one with that shows 9 or 10 ohms can short out the whole bank. Disconnecting the bad one made my car easy to start.
In my experience injectors can leak through the electrical connection area. It's easy to ohm them out, should be 16ish or higher. A really bad one with that shows 9 or 10 ohms can short out the whole bank. Disconnecting the bad one made my car easy to start.
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Safety Car
Joined: Sep 2001
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From: Glenbeulah Wi
The injectors are the problem. They are leaking down causing the engine to be slightly flooded when you try and start it when it is warm. When the engine is cold the additional fuel helps the engine to start quicker. To check this ask the coworker to floor the car when trying to start it warm, does it start quicker? If yes it was flooded. Another test is shut the car off when warm and then immediately restart it, does it start quickly? If yes that means the leaking injectors did not have enough time to leak down and flood the engine.
...spend a bunch of time and money to replace the injectors versus spending 10 minutes to check the FPR first 
