80 vanagon doesn't want to start when warmed up

my recently purchased vanagon starts fine when cold and runs well,but after i drive it for any distance it doesn't want to restart.I can push start it and it runs fine or can spray some starter fluid in throttle body and it fires up.Any clues?

Reply to
guitarman59
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Clarify please:

When hot it will not *crank*? That is, turn the key and... nothing; no starter motor.

Also, is the engine still fuel injected?

Speedy Jim

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Reply to
Speedy Jim

Yes it cranks over but doesn't fire.It has spark at the coil and plugs.As far as I know it is still fuel injected. Thanks

Reply to
guitarman59

There is a Fuel Injection section on my web site:

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Your '80 is close enough to that used on cars thru '79.

The "double relay" gets a signal from the starter solenoid to cause the elctric fuel pump to begin pumping. I would check to see if that is happening.

Once the engine starts and runs, the relay gets a signal from the air flow meter to keep the pump running.

There could be other reasons for no-start, but finding out if the pump runs during cranking is step #1.

You will want to get a Shop Manual, if you don't have one. Haynes has a good one for '80 thru '83: "VW Vanagon Owners Workshop Manual" ISBN: 1 85010 029 2

Speedy Jim

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Reply to
Speedy Jim

I checked out the fuel pump,it's fine.Changed plugs points,and vacuum lines still having the problem when the engine warms up.

Reply to
guitarman59

Hope I don't sound like some "crank" , but did you actually verify that the pump runs while cranking when the engine is hot (and won't start)?

If it really does pump, I would move on to see if there

*really* is spark when hot.

Speedy Jim

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Reply to
Speedy Jim

Do a compression check before you go any further buying things. That engine is notorious for having heat damaged heads. Typical of a cracked head or burned valve (or dropped valve seat) is that it runs a bit rough at low speeds; won't idle at all when really bad; runs great at higher engine speeds; will NOT start once well warmed up unless you get it going at speed and do a bump start. I generally takes about 1.5 to 2 hours to cool down enough to start on its own again. Does this sound familiar?

To do compression check: look at the coil, there are two small terminals with wires attached. One goes to the distributor. Disconnect the wires from the other terminal and either wrap temporarily with tape or otherwise assure they do not contact anything. Remove all 4 spark plugs. Using a compression gauge with a hose extension and the proper adapter for your plug threads, start at the right front (#1). Have someone hold the gas pedal to the floor and turn the key to start position (out of gear, etcetera!) watch the gauge as the engine turns over and over. When the gauge has gone as high as it's going to, tell the helper to stop. Write down the reading for #1 cylinder. Proceed to #2 cylinder and do the same routine - remember to hold the throttle wide open all through the tests. If my suspicions are correct, #3 will be way low.

Note that if the engine is cold when you do the test, the crack may not be as open as when hot (that is why it doesn't want to start hot) You may want to do a hot check, but before you do, you need to loosen the spark plugs a bit while the engine is cold, run it until heated up, then remove the plugs the rest of the way and do the compression check. By loosen a bit I mean about a quarter turn or so - just "not tight" so you don't strip the threads when removing them (Never remove plugs from a hot engine with aluminum heads if they haven't been lossened beforehand. Also don't drive around for days with loose plugs as they will loosen more and then blow out the rest of the way taking threads with them.)

If there are other symptoms you haven't told us like a lot of black smoke when it does start or really rough running, it could be some other things like a bad head temp sensor. If it idles rough, smooths out higher speeds, won't start when hot unless by coasting and bump starting, then the compression check is in order. Hope I'm wrong. -BaH

Reply to
Busahaulic

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