Silly Question but could I possibly have an ECU?

[BOBNKIM]

Strange question, I know but I have an 84 K20 w/502. Bought truck with an OLD analog Projection 4 fuel injection system. Truck runs amazing at full throttle but stalling when slowing or stopping and hard to get going again. I changed all tune up stuff, fuel pump and even new distributor b/c someone suggested it. Still SOS. I called Holley to get troubleshooting help with this analog fi. The guy said I may have a bad ECU. I don't c an ECU anywhere and I'm pretty sure it doesn't have one. Anyone kno where I might look for this? Could it be under dash?

I'm getting ready to change the fi over to a holley demon carb but if anyone has suggestions what else can be causing so much trouble, I'd love to hear it. Plugs are getting trashed right away, even brand new plugs. Truck started running like crap when slowing or stopping, now it's studders constantly accelerating. It runs at idle but as soon as I put in gear or try to accelarate, she dies. BEFORE this it ran great at full throttle but dying at stops. It progressed to where I'm at now. Hoping for suggestions before I pull this old analog off and change to carb.

 

[Frankenchevy]

What about the O2 sensor?

 

[Charlie]

 

[Wumbo]

EFI has an ECM somewhere.

Give ya tree fiddy for it.

 

[Preston]

Welcome from Virginia to GMSB

 

[Shorty81]

Welcome from the Buckeye State. IMO, take off the fuel injection and go carb.

 

[dvdswan]

Welcome to the site.

 

[BOBNKIM]

Doesn't seem to have O2 sensor,

 

[HotRodPC]

EFI has an ECM somewhere.

Give ya tree fiddy for it.

True, if it's EFI but he didn't say anything about E, he said analog. Makes me think it's one of those old 70's system like a Micky Thompson or Moon Racing product kits. We might found out it actually is E though.

 

[HotRodPC]

Strange question, I know but I have an 84 K20 w/502. Bought truck with an OLD analog Projection 4 fuel injection system. Truck runs amazing at full throttle but stalling when slowing or stopping and hard to get going again. I changed all tune up stuff, fuel pump and even new distributor b/c someone suggested it. Still SOS. I called Holley to get troubleshooting help with this analog fi. The guy said I may have a bad ECU. I don't c an ECU anywhere and I'm pretty sure it doesn't have one. Anyone kno where I might look for this? Could it be under dash?

I'm getting ready to change the fi over to a holley demon carb but if anyone has suggestions what else can be causing so much trouble, I'd love to hear it. Plugs are getting trashed right away, even brand new plugs. Truck started running like crap when slowing or stopping, now it's studders constantly accelerating. It runs at idle but as soon as I put in gear or try to accelarate, she dies. BEFORE this it ran great at full throttle but dying at stops. It progressed to where I'm at now. Hoping for suggestions before I pull this old analog off and change to carb.

Do you know the model name or # of this system? 100% positive it's not an Electronic Unit? For sure, if you're ready to throw the towel in on it, don't just trash it and try to remove it carefully. With everyone wanting FI these days, I'm certain someone will take the time and patience to work with it and put it on a square. Give us the name or model # and see if we can't get it going good again. Chances are, it's something minor. 17,000 heads are better than one.

 

[BOBNKIM]

It's an early Holley Project 4 system. VERY old analog system. It was on the truck when I got it.

 

[HotRodPC]

So you probably have the Gen 1 Pro Jection set up. It does appear to have an ECU also. So even though it's Analog, it's still somewhat electronic as far as metering. This might be a little help or at least a place to start.

https://forums.holley.com/showthread.php?18302-Holley-Analog-1st-Generation

 

[1987 GMC Jimmy]

It would be really dumb of the PO/installer to go to all this trouble and not put a control unit in an easily accessible place like under the hood or behind the glovebox. Just because it can be done doesn’t mean it should. It almost sounds like whatever controls it has defaulted to some kind of limp home mode. I shouldn’t make too many comparisons to GM stuff, though, because I don’t have the paperwork on this system.

 

[BOBNKIM]

Can't find any numbers anywhere. Thanks for all the help! Like I said, all tune up componets new, fuel pump new, distributor new. Ran awesome full acceleration, then started dying at stops and had to keep feathering pedal to get it moving again but once I got up to about 30mph, ran awesome. Got progressively worse. Now just running like a dog all the time.

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[BOBNKIM]

Thanks again so much! You've all been a great help!