Engine dies on throttle

[alsgro]

Hey, guys! Wondering if you might have some ideas for me. I've been recommissioning my '81. It sat for about 4 years and since then I've swapped out the fuel pump, changed the wiring to the T-sesor, and also redid the fuse leading to the fuel pump. I got all the old gas out of the tank and put some fresh stuff in. Now the engine starts and runs like a CHAMP. Idles great with little or no misses. Comes up to temp, and the fan runs, etc.

Problem is that when I give it gas, it bogs down and stutters for a 1/2 second. If I apply gradual throttle, it revs up no problem. I thought it was running well enough to pull it out of the garage and give it a spray down... Problem is that the garage is on a GNARLY hill! Engine died, and I damn near drifted back into my buddy's parked prius! Then it would start, but when I tried to give it the beans up the hill, it would die. Luckily, a guy in a big truck saw me struggling, strapped me onto his hitch and pulled me far enough up the hill so that I could back into the garage again. IT WAS LIKE SOME KIND OF MAGICAL FIAT MIRACLE. That you to the stunt driver from Austin who got wrapped early on his shoot that day.

I've checked to be sure the AFM flap is moving, and it appears not to be stuck. Pulled the cap and peeked at the points, looks clean to me. I've had a look through the forum, but can't seem to find what I'm looking for. Anyone have any thoughts?

[courtenay]

Have you checked the connections of the hose thingy leading into the AFM? I had a loose connection at the AFM end and had a similar problem. Any splits or holes in that hose will cause the problem you're having.

[alsgro]

Hey, hi! Thanks for the response. I did crank down on that hose, and i've squeezed it a bit... It feel pliable still, and I don't see any visible cracks.

Thanks for the thought, tho!

Still scratching my head on this one...

[alsgro]

Could this be a bad vacuum advance, valued members?

[wetminkey]

Sure sounds like a timing issue, and vacuum advance (or leak) could cause the symptoms you are experiencing.
Cold engine will exacerbate the problems,...
A timing light will allow you to double check initial timing and watch for advance with rpm.
After sitting for such a long time (especially if there was fuel left in the carb,...probably!) fuel degrades and deposits a varnish (as you obviously know). The carb may just need a carb cleaner spray application,...but may need an air/fuel mixture adjustment, in addition. If the carb has significant varnish, it would need to be soaked in carb cleaner and rebuilt. Not sure if this is your car's issue, or not.
What is your fuel filter's condition?
Wish I could be of more help,...
Good luck with the troubleshoot.
Todd.

[alsgro]

Thanks so much for the reply, Wet. It's a FI '81, so no carb issues, but I guess it's possible that the injectors could be clogged up with the same varnishy gunk?

I must confess to not owning a timing gun, and I'm not sure I wanna drop the coin on one. But I think timing could certainly be the issue. Although, it's just been sitting, no one twisting the distributor or anything... Hmm...

[GeorgeT]

"I must confess to not owning a timing gun, and I'm not sure I wanna drop the coin on one. But I think timing could certainly be the issue. Although, it's just been sitting, no one twisting the distributor or anything... Hmm..."

Timing lights are fairly inexpensive ($20 - $90 or so). I use an inexpensive one that doen't have a tachometer and it works well. You will be hard pressed to find a mechanic who will adjust your ignition timing for $20. The hard part is loosening the hold down bolt.

[wetminkey]

I second GeorgeT's post.
I even have a single lead timing light that runs on D batteries (for my 6V tractor, primarily). Cheap,...on the internet!
The timing may be dead-on, but you'll not know without a light. You can troubleshoot from there,...
And yes, I would guess that the injectors could become varnished. (I run fuel stabilizer in my injected vehicles to prevent that problem,...but I've also NEVER had a problem with those vehicles, only carbs.) But check the easy stuff first.
Fuel injection reduces the possibilities (at least the probables) to timing or vacuum leak. As long as there is no reason for it to starve for fuel at throttle,...
Best of luck with troubleshooting!
Todd.

[alsgro]

Thanks, again. I’ll get back to fiddling with the old girl soon. Oh, hey... I forgot to mention that it did backfire a few times when I tried to drive it. Does that help the diagnosis at all?

[GeorgeT]

"Thanks, again. I’ll get back to fiddling with the old girl soon. Oh, hey... I forgot to mention that it did backfire a few times when I tried to drive it. Does that help the diagnosis at all?"

Backfiring is a sign of ignition timing that is off.

[alsgro]

Yo. Where do you guys hook up your timing light leads? Is there a sneaky place to take + & - power under the hood, since the battery is in the trunk???

[aj81spider]

I actually wired in a harness that I can plug into. Before I did that I picked up power from the alternator stud (on my engine it's on the passenger side - easy to get to) and ground from a random mounting bolt on the fender.

[RRoller123]

http://www.fiatspider.com/f15/viewtopic ... ming+light

Here is some more on the issue.

[lglade]

With the engine idling, you can spray around the various hoses & plenum with propane, starting fluid, car cleaner, or even WD40 to find a vacuum leak. It's an easy check and one that you should accomplish before making adjustments to anything else.

https://www.youtube.com/watch?v=sa8Yu1oCTVI