1981 Fiat Starting Problem

[ronj81]

Hi,

I have 1981 Fiat Spider FI and having problem of starting the engine.
Last week the car was working fine but this morning I attemp to start the car but does not start.
The car start but it does not turn or should I say it start then turn off right away. I have this same problem before but somehow the problem comes and go. I replace the fuel pump, fuel filter but no luck. When I force it to turn - it back fires. Can someone help please...

I also check the hose from air filter to the head and no damage.

Regards,

Ron J

[So Cal Mark]

do you have a test light or voltmeter to use for troubleshooting?

[ronj81]

Hi Mark,

yes I do have test light and DMM.

[rlux4]

Are you saying that the engine is turning over (cranking) but not firing (running)?
You need three things for an engine to run (assuming you have adequate compression and fresh air supply)
1. fuel
2. spark
3. correct timing.
If your car has this problem intermittantly I would concentrate on 1 and 2, the timing will not come and go. Unless you have a loose distrubutor; unlikely, but possible.

1. Fuel: on your FI system you can disconnect the fuel line that goes to the cold start valve from the fuel rail. You should see fuel squirting when you crank the engine. Pull the coil wire from the center of the dist. so that the car doesn't start while you check this.

2. Spark: Pull a spark plug and touch the metal base to a bolt or something metal on the engine. You should see a good spark jump across the gap between the electrode tip and the bent piece of metal on the end of you spark plug when cranking.

There are two kinds of timing on our cars, valve timing and distributor timing. If you have good fuel delivery, and a good spark then it's time to check the timing.

One last thing, in rare cases, these FI systems can supply too much fuel, as was the recent case with kristoj, where his cold start valve was open when it didn't need to be (faulty thermo time switch) which was flooding the engine.

Good luck
Ron

[ronj81]

Hi Ron,

I performed test on 1,2 (fuel and Sparks) i full out the fuel like from the cold valve start and start the engine - there were a lot of gas came out when I crank the engine. I also pull out one of the spark plug and crank the engine there a good sparks that came out.

Could it be that my cold valve is faulty?

[ronj81]

One more thing when I further look into the cold start wire - I started the car and somehow it the engine turned but was hearing as if the key did not move back from cranking position - the started was still turning. I turned it off and crank it again and this time it did not start back to square one. With this I came to realize that the engine is getting sparks, fuel.

[rlux4]

You have two separate problems. If the starter doesn't disengage from the flywheel (keeps on cranking after engine has started) you have a starter problem. This is not a factor related to the engine not starting.
When the car doesn't start are you smelling fuel? In kristoj's case his cold start valve was open when it didn't need to be (it wasn't cold, when it would need the extra fuel the cold start valve supplies) because the thermo time switch was faulty. That was flooding his engine. Too much fuel in the fuel/air mixture and it is "flooded", and won't start. This could be your problem. Disconnect the wire connection going to the cold start valve and see if it starts OK. If it does, that's your problem also. If it doesn't start, then you need to check all your rubber connections on the air supply ducting. Check your AMF flap, be sure it's moving freely.
You have spark and fuel, you're going to check that you don't have too much fuel, and that you do have the correct amount of air for the fuel/air mixture ratio.
Ron

[ronj81]

The car doesn't start when I remove the wire from cold valve socket - I don't smell fuel when I try to start the car. I feel that this is a wire issue but don't know where to begin.

[rlux4]

OK. If you are getting fuel and spark, it may be that your injectors aren't pulsing. The only way I know to check this is to pull an injector, point it toward a container and crank the engine. You should get a spray that pulses (squirt-off, squirt-off)
It should not be a stream of gas, but a spray. If the injectors aren't pulsing it could be a relay or in rare cases the ECU itself.
Ron

[ronj81]

Hi Ron,

I will check that - in the mean time I recheck all the hoses and found that the hose that coming from the VACUUM or BRAKE PUMP? is loose - I mean the mounting where the hose attached to are loose. Would this cause for the car not to start?

[rlux4]

A vacuum leak won't cause a car not to start. It would cause it to run poorly after it was started. Vacuum is not one of the three things you need to have an engine run 1. fuel 2. spark 3. timing. Vacuum is used to advance the distributor during acceleration. The car would still accelerate without the vacuum, it would not do it as smothly or quickly though.
Ron

[ronj81]

Hi Ron,

Thanks, I will buy ECU from the junk yard and see if that would help. The fuel relay I know is good because I have two of them and one of them is brand new. Any other place I can look into?

Rgs

[rlux4]

I wouldn't buy an ECU until all the other possilities were ruled out. These ECUs are pretty bullet proof. It may be the problem, but going by the odds, it's not. Have you checked that all the ducting from the AFM to the engine isn't loose? Have you checked that you have full & free movement of the flap? A while ago my car was accelerating poorly. When I took the housing off and checked the flap it was hanging up after only opening about 1/4 of the way. If yours isn't moving, it's not getting air. Have you checked your valve timing and the distributor timing?
Ron

[ronj81]

AFM is freely moving, Valve timing, Dist timing should be good because I took this car to the mechanic just two weeks ago. I am currently reading on Fuel Injection Diagnosis and following every step - I do have a question, does the fuel pump should making noise when you have the eng key to on for about 5 sec? Because I am not hearing anything on mine.

[rlux4]

There's a good thread on these FI systems here:
http://fiatcenter.com/bbv2/bbBoard.cgi? ... tid%3D2913
Another problem I experienced is a blown fuse that is found behind the fuse panel. It is an inline fuse with a brown with white wire, you'll it find amongst the mass of wires behind the fuse panel, under the dash.
Yes, the pump runs a few seconds when you turn the key on to build up the necessary pressure in the system. Then it shuts off until the car starts, at which point it runs constantly.
Once I had to tap the fuel pump to get it going, since then I've never had that problem again. Because you said you had fuel at the cold start valve line, I didn't think it was the fuel pump.
Ron