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Discussion Starter #1
I have a gas truck, 1.7 engine. Some component in the fuel or ignition system seams to be the cause of stalling. The engine will stall after driving a while on a hot day. I suspect the ignition switch, the coil, the fuel pump relay wires, and possibly the ignition control unit. The ICU gets hot and has a heat bank. The fuel pump relay and wires at the fuse box behind the relay seem to get unusually hot. When the engine first stops and I try to start it again, I don't hear the pump kick in. It seems to work again after cooling for a few minutes the fuel pump relay has a wire to the coil and one to the ignition switch. The factor that instigates the stalling seems to be driving for awhile in extreme heat---the fuel pump cuts out. I guess there could be a problem with the pump itself or the fuel accumulator, but both are fairly new. When I jump the fuel pump at the fuel pump relay socket, the pump runs, but I still can't get the truck started until it cools for awhile. so I suspect some other component or wiring. Maybe someone can help pinpoint the problem area before I do a lot of testing with a multi-meter, something that seems hard for me to master.
 

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If the fuel pump isn't whining (they let you know when they are hot). This sounds like it is the Fuel pump relay and cold soldered joints on the pins very common on CIS cars, folks with Cabriolets usually carry a spare. To test when it fails remove the Fuel pump relay and place the horn relay in it's place, car starts and runs it is the Fuel pump relay.
Or replace it with the same, and then you can remove yours and try to desolder the connections and resolder them...

www.cabby-info.com has the different types of Fuel pump relays and part numbers for them as not all fuel pump relays are correct.
 

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Discussion Starter #3
Thank you. At this point, I'm suspecting the pump. When I jump the fuel pump relay socket, the pump runs but the truck won't. I changed tanks (used) recently and I suspect there may be contamination in the pump that's causing it to overheat (debris from the used tank). I recently read that pumps fail from overheating due to contaminated fuel. Maybe the fuel accumulator has also been compromised.
 

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Discussion Starter #4
I now have new considerations, but it still may be the pump or check valve. When the engine gets up to temp, it shuts down, regardless of the temperature outside. It then will not start until it has cooled down for quite a while. I guess it could be the warm pressure regulator, the pump getting hot from contamination, the position of the sensor plate, a bad starter, a bad alternator (the alternator gets very hot on the casing), or? Any help would be appreciated. I have also thought the coil or distributor might have some effect once the engine warms up (?).
 

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While I am not a CIS Guru, as yours isn't a Digi, and I have a lot of weird things happen to mine. I can try to help.

I now have new considerations, but it still may be the pump or check valve.
Pump over check valve. The Check valve should be internal to the pump.... So I would have to ask that if you break the fuel line at the filter inlet when this occurs, and it weeps or fuel flows freely, then you can discount the back end. It could be the accumulator as I under stand they have issues on CIS.

When the engine gets up to temp, it shuts down, regardless of the temperature outside. It then will not start until it has cooled down for quite a while.
If it Cranks but doesn't catch it isn't the starter.


I guess it could be the warm pressure regulator, the pump getting hot from contamination, the position of the sensor plate,


The WARM Up Regulator isn't used when hot, as it shuts off, so I am suspect of that being the issue.



a bad starter, a bad alternator

(the alternator gets very hot on the casing),


If your Battery is getting a charge, then it isn't the alternator they can get toasty warm, but you can have it tested, and have them do a few tests to verify that it is functional when hot or that it drops.

Batteries, are about the same if they short then you should see it in a specific gravity test, and you can take it to have it checked.
Batteries can open up the ground thereby isolating the engine and things.


I have also thought the coil or distributor might have some effect once the engine warms up (?).
Dizzy's usually flake out, or go out completely, they don't go iffy....and while they are solid state, the units are built to take that into consideration.
Coils are wire, and oil filled (used to be PCB's) not so any more and I have hear of them cutting out, but not as in heat related, and a coil once it goes, it is usually bye-bye kind of thing.

Found this, searching the tex for CIS and no start when hot.
My buddy Ron explains things a wee bit and is a good read, it may narrow your search, but as in all things read it fully.
http://forums.vwvortex.com/showthread.php?6020779-1988-Cabriolet-Hot-Starting-Issues&highlight=CIS+engine+cuts+out+when+warm

Could be vapor locking when hot, or not holding residual pressure when warmmmm read through the link, and try the tests....
 
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