87MagnumII

Friend of mine as a 1996 baja outlaw. When he bought the boat earlier this year it had a 2bbl carb setup on it. He switched it to 4bbl but didn't bother to set the timing with a light when he put it back together. I went by today to help him but I'm unsure of the ignition system. I am familiar with TBIV but I'm thinking it's possibly a TBV, which I know requires a different timing procedure. It has the ignition module bolted to a bracket behind the dizzy, not on it but behind it. When I pulled it out to look at the only number I could find on it was 807264-3 which shows up as a merc ICM but doesnt tell if it's IV or V. The engine serial number is OF881998. I'd anybody can help decipher these numbers and let me know what I'm working with it would be great. I do know that I put a light on it at idle just to see what it was reading and it showed 27* but I don't know if that was accurate because I didn't ground any wires out if it is a TBV ignition to put it in base timing mode. Any help would be great, he wants to be tuned up and on the water Saturday so we are hoping to figure it out by then.

lakematdude

Engine serial number 0F881998 is a 1996 Model number 457B100JS MERCRUISER "TB5", W/PS, TWOPCEX, 5.7L ALPHA.

So yes it has a TBV and needs to be grounded.
Timing at Idle RPM: 10° BTDC
Idle RPM in Neutral Gear: 650

87MagnumII

Thank you. Did they make a tb5 without a knock sensor? Also I've read some on how to ground it out but I'm unsure about the jumper wire and what not. Any chances you could explain the process in stupid people speak so I can get a grasp on it? Lol

lakematdude

This should help you set the timing,
http://www.boatfix.com/merc/Bullet/94/94_02.pdf

No this engine should not have the knock system on it, If it was the 5.7 LX engine then it should have one.

87MagnumII

Cool deal, thanks again for your help.

87MagnumII

Went back over to his house tonight and got the boat running good. Took the cap off the dizzy and confirmed #1 was at TDC by checking pointer orientation against the timing marks and looking in the cylinder at the top of piston. After the was done I started checking plug wires and what do you know, somebody had crossed up #2 and #4. Got all the plug wires where they needed to be. Found the end of the purple and white wire to ground the ICM and put a jumper wire in it and grounded it. Fired it up and it purred like an engine should. Got the timing and idle adjusted and closed the hatch and called it a night. What's amazing is he had been running for a month with plug wires screwed up and couldn't figure out why it didn't run right. I'm no professional but I just don't think there is hope for some people

Any way thanks for all the pointers and advice, made my life easier and I learned something new, I consider it a win win

Mbam

Nice job! Back to the basics!