I'm helping Jibs trouble shoot his 1978 Brat. This problem has got me a little baffled. It starts right up, idles for about 20 seconds then the engine dies. It's like someone turned off a switch. It will fire right back up then after 20 seconds it will die again. Problem repeats it's self. Just before the engine quits it the idle goes up and it runs really smooth (not missing) for a fraction of a second then dies.

 

I check the coil, fuel pump, spark...etc. I found out the alt was dead, maybe when that died it fried something?

 

Any suggestion would help us get his brat back on the road

 

Thanks,

Jeremy

might want to check the voltage regulator on the passenger side of the engine compartment. If the alternator spikes too much for too long, it'll kill it, and this is where the fuel pump is wired to the alternator

That's sorta what mine will do, but I have to keep the throttle open to keep it running.

 

For what it's worth, I already know my voltage regulator is bad (and the voltage regulator contains the fuel pump relay), as I have to hotwire my fuel pump directly to the battery to get it to run.

Hum... so maybe it is the fuel pump. I'll look into that somemore. It still dies if it's at idle or WOT.

Yes, i vote for the fuel pump as well. hard wire it and see if things change.

 

-Brian

my advice from a previouos thread on a similar problem:

 

 

My experience from My 1980 4wd wagon. The output of the alternator is used to keep the fuel pump going( a crash safety shut off thing). So if alt quits then fuel pump is shut off. So perhaps you did not actually run out of gas, even though symtoms the same?

 

I had an intermittent alt that drove me nuts on way home one night, would work for 1-5 minutes before shutting down and having to coast off road. But in "start" position the pump operates so could get going. FINALLY figured out what was going on and had wife bring me tools and a piece of wire to hot wire the fuel pump to get me home. I replaced regulator but took the alternator replace to fix it. I also wired up an override switch to at least be able run on battery power, and two years later was used when my belt broke in traffic. Kept going until could pull off and replace with the spare I always carried.

 

As far as location of regulator, I believe it was on fenderwall near front corner-cont remeber if on drivers side near the jack or behind the battery on pass side.

 

Again, this was on my 1980, dont know if applys to yours

As far as location of regulator, I believe it was on fenderwall near front corner-cont remeber if on drivers side near the jack or behind the battery on pass side.

 

 

Yup,right on the passenger side,near battery and front of shock tower.I'd suspect a bad v/r or alt.

Wow I think we are getting somewhere now. Thanks a bunch. I'll look into it this weekend.

Does anyone see a problem with installing a alt form a 1984 EA81 with the voltage regulator built in? I have one laying around and I would like to use it for testing purposes.

Just want to double check. The voltage regulator is the gold box screwed to the fender wall right?

 

That's it,correct.

 

Search the archives for the thread on upgrading to electronic ignition.

 

For now,maybe take the v/r off and clean up the connections,check underneath and make sure it's not gummed up and that the capacitors,etc. are still looking good and all soldering intact.

 

I'm really needing to run,otherwise I'll check the FSM for you later tonight.

The problem is in your faulty alternator! If the alternator is NOT working your fuel pump will only work for a second or two! Had the same problem about 10 years ago on a 1979 4X4 wagon I had. Hard wired the fuel pump and it would run forever. Problem is that's not good for the fuel pump. When you turn on the ignition the fuel pump is energized. Then when no juice comes from the alternator and you run out of that little burst of fuel, the motor dies. Replace your alternator and your problem will be solved.

So, if I hotwire the fuel pump and I can still only get it to run for about 20 seconds, then I must have another problem.

So, if I hotwire the fuel pump and I can still only get it to run for about 20 seconds, then I must have another problem.

 

correct. let us know how it comes out.....

I haven’t quite got to the stalling problem yet. I had some issues with the cooling system I have been working on... but I'm almost to the point of installing the new alt.

I haven’t quite got to the stalling problem yet. I had some issues with the cooling system I have been working on... but I'm almost to the point of installing the new alt.

 

probably be your best bet. When you crank over the engine with the ignition, the fuel pump is driven off of the ignition. When the engine is running and you let off the key, the fuel pump gets its power from the alternator. If the alternator or v/r are bad, the fuel pump won't run, so it will drain the bowl on the carb.

correct. let us know how it comes out.....

 

I'm fairly sure it's a carb issue. We are talking about Hitachis here

All done. Swapped that new alt in and it runs like a champ! Thanks for the help everyone.