[largeal]

Well...Mopar MPI/4.0 HO head is finally installed and ready to fire it up. Didn't get very far though.

Fuel pump didn't turn on when I turned the key to "on". Hooked a voltmeter up to the pump wiring and only get a momentary 12V bump, then it drops to zero. The new MPI relays mounted on the firewall, double-click as the volts drop off.

I have the MPI solid red wire hooked to a constant 12V source (starter relay feed) and the MPI yellow wire hooked to a red/wht wire coming out of the fuse block that is no longer used ( I think that it powered the old ignition module). I'm reading a constant 12.5V at the starter relay. The red/wht wire is 12.5 with ignition key in the "on" position, and drops to approximately 10.5V with the ignition switch turned to "start" and cranking the motor. So I'm kind of at a loss as to why I'm not getting power to the fuel pump.

I thought about going direct to the fuel pump with B+ but wanted to see if someone here might point something out I may have overlooked. Another Jeeper had a similar problem but found out he had his starter relay wired wrong. I'm hoping mine will be as easily fixed. What really gets me is that there are only two wires that interface with the old wiring, and it's pretty straight forward. Other than that, I haven't attached the "check engine light" and the "tach lead" wires yet.

I really need to get this thing running as I'm leaving "paradise" soon and relocating back to the mainland. Any ideas/thoughts ???

Thanks, Al

 

[jdoggmoney]

This is only a guess and others will probably figure out the real cure but... Does the MPI need a signal from the tac lead to tell it that the engine is turning/trying to start? Maybe it's shutting itself down thinking that the engine is not being started.. so as to not flood it??? Good Luck.

 

[largeal]

The assembly instructions have you bleed the rail before you start the engine, and then once running connect the tach wiring. This is due to the fact that some tachs have a low impedance and will short the coil to ground. It doesn't harm anything, but will prevent the engine from running.

 

[lomodyj]

Don't know your answer, sounds like you did it all correctly...try emailing Hesco (builder of the kit) at [email protected] it usually takes them a day or two to get back to you but Bennie seems to know his stuff.

 

[largeal]

Re: Yep...roger that...

first thing on the "to do list" for this morning. Thanks!