KSA

I have spent the last hour or so checking old threads here and at crawler. Here's my problem. My winter project to install a newer motor and gut a non working TBI on my 1981 is turning into a spring project! I got the rig running last week, but it won't stay running, fires right up, runs for 30secs to-1.5 mins then stalls. New 32/36 weber, electric fuel pump from the previous mod is still being used. The fuel pump was providing higher pressure to the throttle body, so I installed a pressure regulator in line that is around 3-3.5 lbs. Battery is fully charged but not charging as much as it should from the alternator (I decided to convert over to the internal regulator that was still on this motor when I bought it, but haven't figured the full wiring set up yet.) I doubt that is part of the problem, but figured I'd throw it in anyway. I don't think it's a vacuum leak, when the rig starts, it starts normally and runs fine for the short amount of time that it does run. I used the weber dvd and utube to plumb in the carb, I'm fairly certain it's correct. If anyone has an idea I would sure like to hear it. I'd like to catch some snow wheelin before end of winter. Thanks...

cars-guy

If you give it any gas does it still run normally or only at idle? right now it sounds like its not getting enouph fuel. The electric fuel pump will fill the carb up when the motor stops but maybe the motor is pulling more fuel then system can deliver. I would check all your fuel lines and change the fuel filter to start.

L5wolvesf

I can't say if this is the cause of the problem(s) but 3-3.5 psi is too much on a 32/36 Weber - recommended is 2.5 max.

KSA

Thanks for the help guys, I appreciate it. I replaced the fuel filter as a suggestion from my thread search a few days ago. I can operate the throttle by hand and the rpms do increase cars guy, just stalls after a minute or so. Always restarts right after stalling. I installed a pressure regulator between the pump and carb. On one of the outlets I plumbed in an oil filled pressure gauge to monitor the pressure. The other outlet has the outgoing feed line to the carb. Not sure if this is as accurate as inline on the carb feed side. I watched the pressure go up to 6psi at start up, then down to zero while the rig was still running. The pump was working well when I parked it last year, so I'm thinking it should be fine, it is putting fuel to the carb. I am wondering if the pump was specifically for a throttle body due to higher pressure fuel psi needed to run the tbi "injectors". I guess i'll unplug it tomorrow and look at the fuel flow, see if it's steady or sporadic. Thanks for the heads up L5wolves, I thought the weber ran 3-3.5. the regulator was factory set at that rate when is was mailed to me, I didn't want to fiddle with it until I had it narrowed down more.

bootscootboogie

iTrader: (1)

I would want a mechanical fuel pump personally. They are not expensive at all. Maybe that electric one is getting too hot from being regulated and not pumping out what its designed to?

Co_94_PU

iTrader: (-1)

This does not sound right. Go over your aftermarket part paperwork again, see if maybe you are monitoring the return line or a similar problem.

Check what is going on in the float bowl just before, during, and after the stall out

L5wolvesf

This, plus I think we need some pictures to see what you are talking about.

KSA

All good suggestions guys, I will take pics tomorrow after work. I plugged the return line from the TBI as per weber. I pulled the plug last night, didn't change anything. I don't think the fuel pump is running long enough to get hot. I think I should plumb the regulator into the feed line for a more accurate measurement. The only other thing I can think of is that the Fuel pump suction pipe in the fuel tank had to be enlarged in order to feed the TBI fuel pump. That's what the the guy told me, not sure if its theoretically true, but it does have a modified pick up tube. I'm using the same fuel line, pump, filter alignment as previous and getting fuel to the carb, so it should be runnable. I tied the hot wire from the pump into an ign hot harness wire so unless I'm getting voltage fluctuations from that wire the pump should work well enough to keep the old boy running. Will post pics tomorrow, thanks again gentlemen

KSA

here are some shots of the engine compartment, tried to get an angle on the possible problem areas

KSA

Talking with a friend at work, he suggested checking ecm and ignition. I have a spare ecm that I looked at, just don't see how this would be tied to the spark side of the engine, it does start right up and when it stalls, it starts again. Just won't run more than a minute, seems to run a bit longer if I operate the throttle linkage at a higher idle. I disconnected the fuel hose after the regulator and ran it into a coffee can for thirty seconds or so, the flow did not fluctuate at all. I thought maybe the coil might be getting hot (bad coil), but I think not, it restarts right after stalling, which wouldn't give the coil enough time to cool off if it was bad. Ignition??? maybe, but this run time is pretty consistent almost like a small component is getting hot or maybe sending a signal to another component of the spark side of the engine. Any ideas? I can dive in and try anything, been in the shop too long. Thanks guys.