I frequently have a problem starting my 94 Jetta, Multi-port fuel injection when the car is hot and has sat for about 5 minutes. The engine turns over fine, but will not fire. It sounds like the car is starved for gas.
I've recently tuned the car up: plugs, rotor, cap, but the problem still exists.
Sounds like vapour lock. Check how rapid the fuel pressure drops after you shut down.
SFC
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fuel pumps working? fuel filter new?
you need to double check for spark at the plugs. I have had an ign coil make an engine hard to start. Spark was there but very weak!
later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris
The car does run, it's just hard to start when it's hot. Would a fuel pump perform differently if the engine is hot?
Yes, I replaced the fuel filter.
This is almost always a vapor lock issue.
Yes it is possible to have a problem starting the engine if the transfer pump is not functioning well and especially if the fuel has been heated up slightly by the heat from running the vehicle. This would be similar to Vapor Lock. A fuel pressure test should tell you something.
Don't forget about a weak spark causing problems too! ;-)
later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris
That only happens with carburators from what I can remember.
Kinda true, but the fuel lines are still protected against heat for the fuel injection systems. I would assume that heat might cause problems like they had with the carbs and vapor lock.
That fuel should recycle back into the tank heating up that fuel slightly and possibly the lines around the engine or exhaust components may heat up the fuel when the engine is off. Heat is what basically causes vapor lock. I would think it is possible that vapor lock could occur with FI systems also, or maybe I should say that it is possible that the fuel at the injectors might have turned into vapor while the hot engine is off.
I would still suspect an ign coil problem though! ;-)
later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris
Any suggestions on how to solve this on a Jetta?
You need to check the fuel pressure. Residual fuel pressure, when the engine is off, should remain at a certain psi for a certain period of time. The Bentley manual should explain how to test this.
If the residual pressure test fails then the problem could be the fuel pump check valve or the fuel pressure regulator or leaking injectors or ???
You should also check the ignition to make sure the plugs get good spark. I have seen some new ign. coils fail, they would send spark to the plugs but the spark was too weak to allow the plugs to fire under compression.
later, dave
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