502 fuel injected spudders and dies randomly
07-15-2014, 03:20 PM
#11
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run on portable gas tank supply and new fuel line to take that end out of the mix for a problem area or is the problem area. IMO you might need your injectors tested / flowed / cleaned and flow tested for the final results. That's how they are done in that order.
before that you need to test your fuel pressure.
before that you need to test your fuel pressure.
07-15-2014, 03:39 PM
#12
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good feedback here is to clean injectors and test fuel pressure including running on an extratank to eliminate fuel as the culprit..
I had a similar problem as you and it kicked my butt for sometime until I studied how my 99 502mag got its spark, my problem ended up being the secondary coil inside my distributor working intermittently, maybe swap out your dizzy with another known good one to see if your dizzy is the culprit.
I also know that testing and testing everything is a hassle but its about the only way to figure out intermittent problems. I have also seen electric tachs cause problems like you mention, so pull the power to your tach and see if problem goes away.
I had a similar problem as you and it kicked my butt for sometime until I studied how my 99 502mag got its spark, my problem ended up being the secondary coil inside my distributor working intermittently, maybe swap out your dizzy with another known good one to see if your dizzy is the culprit.
I also know that testing and testing everything is a hassle but its about the only way to figure out intermittent problems. I have also seen electric tachs cause problems like you mention, so pull the power to your tach and see if problem goes away.
07-16-2014, 04:45 AM
#14
You likely have the VST system without cool fuel. Cool fuel came about much later. Pulling injectors is intimidating but its not rocket science. At a minimum you will have clean, proper flowing injectors and a know base line. Best case you solve your problem.
The fact that it sat for a few years would point me towards a fuel system/injector issue. The fact that you can only pull 4000 rpm would lean me towards a fuel issue. If your injectors were clogged, partially clogged, or if even one was not running to full capacity would lead to a lean condition. A lean condition would lead towards engine knock. Engine knock retards timing on MEFI motors. Retarded timing makes the motor lay down on the top end (hence the 4000 rpm wall). It also elevates the exhaust temps and has the potential to hurt valves, pistons and valve seats.
It MIGHT be ignition, but I'd start with fuel stuff first.
Best of luck.
The fact that it sat for a few years would point me towards a fuel system/injector issue. The fact that you can only pull 4000 rpm would lean me towards a fuel issue. If your injectors were clogged, partially clogged, or if even one was not running to full capacity would lead to a lean condition. A lean condition would lead towards engine knock. Engine knock retards timing on MEFI motors. Retarded timing makes the motor lay down on the top end (hence the 4000 rpm wall). It also elevates the exhaust temps and has the potential to hurt valves, pistons and valve seats.
It MIGHT be ignition, but I'd start with fuel stuff first.
Best of luck.
