1994 PLP multi coil pack testing protocol

Welcome Kiwi Dave.

A 1994 "PLP" engine with the 4-pack coils has the Pro-Tec engine management system that PCM developed in the early 1990's. Many PCM engines of that vintage had the Pro-Tec installed. I'm part of the Pro-Tec club as I also have a 1994 Ski Nautique with a "PLP" engine that came from the factory with the Pro-Tec system.

The symptoms that you are describing are consistent with a Pro-Tec that is dying. My experience was similar. Start, then no-start. Then for no apparent reason, start again. Eventually, the Pro-Tec on my PLP engine finally died in the middle of a very large lake. I had to be towed back to the marina. No joy there.

Now for the fun part...repair parts for the Pro-Tec system are no longer available. I called PCM and spoke with one of their senior technicians who was very familiar with the Pro-Tec EMS. He recommended that I completely remove the Pro-Tec system and retro-fit the engine back to a distributor based ignition. So, that is exactly what I did. As it turns out, several members on this forum have done the exact same retro-fit. The link below will take you to the discussion containing pictures an a tidy write-up of the procedure.

LINK to Pro-Tec Swap-Out Thread

Good luck.

JQ

They quit making PCM kit , I think your 2 options are DUI distributor or MSD marine kit pretty much at this point . It a much happier engine with the old style setup. starting is much improved no random backfires. Make sure you close down the gap when you put new plugs in upon install. its a smaller gap on regular distributor. Just use an earlier year for reference.. Only difference in system is you have low pressure electric carb fuel pump.

I believe DUI wants a .055 gap.

DUI gap recommendation is 0.050 - 0.055

rosconole wrote: They quit making PCM kit , I think your 2 options are DUI distributor or MSD marine kit pretty much at this point . It a much happier engine with the old style setup. starting is much improved no random backfires. Make sure you close down the gap when you put new plugs in upon install. its a smaller gap on regular distributor. Just use an earlier year for reference.. Only difference in system is you have low pressure electric carb fuel pump.

Roscoe

You once again have a gap in your info

A ProTec 454 had an electric fuel pump to supply the carburetor, a ProTec 351 with a carburetor has a mechanical fuel pump

Another distributor choice is a complete Pertronix marine distributor for a 351w (only for normal rotation like Kiwi Dave's PLP engine.

I have seen some that had an electric low pressure pump so , maybe in the change over year to year. .035 on the plug gap NGK usually comes out of the box around .036. , .050 is a little much for good idle quality from ones I have seen run. Maybe the DUI runs hotter and that is alot for any naturally aspirated engine, but I would bet if you close it down you would be suprised. I didn't recommend Pertronix because they have been not as reliable for me and a few other people. Its a decent product , Just support and reliability is not as good. I talked to them personally at trade show and they were not focused on marine market.

Ross presents good info to show folks what not to do. So there's that?

Would be safe to say read the recommendation then do the opposite and you're golden,

rosconole wrote: I have seen some that had an electric low pressure pump so , maybe in the change over year to year. .035 on the plug gap NGK usually comes out of the box around .036. , .050 is a little much for good idle quality from ones I have seen run. Maybe the DUI runs hotter and that is alot for any naturally aspirated engine, but I would bet if you close it down you would be suprised. I didn't recommend Pertronix because they have been not as reliable for me and a few other people. Its a decent product , Just support and reliability is not as good. I talked to them personally at trade show and they were not focused on marine market.

Rosco

You've seen an electric fuel pump on a carbureted ProTec 351W, but......I've seen Elvis a few times myself..

I have to admit, I went out and looked at my old truck that has plugs gapped at .060 factory spec. I was looking for a supercharger or maybe a turbo that I never knew was there

It wasn't there, what gives?

By the way, I'll give you extra points for entertainment value, not many but a few. You do keep me laughing after all.

rosconole wrote: You should open your own Marine mechainic shop since you are all know on everything. .

rosconole wrote: Or was it a F150 that shoots spark plugs through the hood.

The coil kept the plug in the hole so no hood damage. Don't ask me how I know that!

Also, I may have a couple of working protec units available this summer. I just ordered the parts for a DUI conversion. Boat still runs fine but I retired a few weeks ago and needed a project.   I would prefer to give the parts to someone with an EFI boat since the carbed boat conversion is pretty cheap and easy. I will post them when I finish the swap.

I think the relay for the ignition is a good idea. When I do the swap I plan on adding two relays for the ignition voltage. One N.O. in series with one that is N.C . The N.O. relay will be closed by the key switch voltage probably similar to what you did. The N.C. will be connected to the existing over temp and low oil pressure switches. If one of them detects a fault then the engine will shut down. The switches are open until they detect a fault then they connect to ground so the connection would be to the low side of the relay control.