Stuck at 2500 RPM- 87 Martinique 454

I purchased a 1987 Martinique with a rebuilt 454 about a month ago and have yet to get it going right. At first, the marina told us there was a small carb problem, but because it was not running right, I got a great deal on it. The boat had been sitting for two years so we figured a quick carb rebuilt, fresh gas and plugs and I would be on my way. Since I brought it home, I have replaced the distributor (the PCM recommended Mallory), coil, plugs, wires, thermostat, impeller, fuel filter, and carburetor. At first, we thought it was just a timing issue since the centrifugal advance in the Prestolite did not advance. After we straightened that out, we purchased a Holley 4160 650 cfm through SKIDIM. This is the PCM factory replacement carb. Once we put that on, I had it running great for a couple hours then the engine began flooding. Gas would drip into the primaries even with the boat off, so we had a new carb sent out and same problem. We have messed with the timing and the carb but still cannot get about 2500 RPMs while in gear. In neutral, the engine will rev up without a problem. I have talked to so many people about this boat (SKIDIM, Correct Craft, PCM, other PCM dealers) and am running out of ideas. According to the rebuilder, a new cam was not put in, but they replaced the valves, pistions (and bored them out), lifters, and intake (an Edelbrock performance intake). The rebuilder as well as the owner who traded it into the marina both mentioned there had been a carburetor problem but both figured a rebuild would solve it. The carb was so bad it could not even be rebuilt, but even with a new one, still no luck. At this point, having two new carbs and the same problem, I think I can safely rule out that the carb itself is the problem. Possibily the carb will not match up with the intake (I have the metal plate that SKIDIM recommends) or the engine somehow. Any help would be greatly appreciated. Thanks. Scott

Yes, I had it up to full speed and 4400 RPMs. When you went from zero to full speed, it had a slight pause, but I hear that is how all carbureted engines are. So basically, it ran great.

We actually checked the mechanical timing and the cam and crankshaft marks do line up, so that has been ruled out.

The carb I put on is brand new and replaced a brand new one and they are both from PCM and PCM and SKIDIM both tell me that they come calibrated for my engine. I do have a rubber fuel line after the remote filter. I took that off to inspect it when I changed the filter and it appears fine. The fuel line between the pump and carb has been replaced and I have added a fuel regulator (I was getting abotu 7 psi of pressure and now have it between 5-6 where it is suppose to be) and an in line fuel filter.

Thanks for the response.

Scott

I have been talking with Holley, Vince at SKIDIM, Max at PCM, and Bruce at Midwest Correct Craft. They are all telling me that aside from the idle mixture screws and main idle adjustment screw, I should not have to make any other adjustments. I considered some other adjustments you mentioned after reading the manual but not sure what really to do.

The engine had been rebuilt before I bought it. He told me the cam was in great shape and he could not find a performance one (he is a car guy and the engine is reverse/right hand rotation) that would be better. The story I got from the previous owner (he had already traded it in the marina so had no real reason to lie) and the rebuilder is that the engine had not hatched, but instead the owner just wanted to supe it up. I know that does not make sense, especailly since he paid all that money and did not get a new cam, but that is what I have been told.

I just got off the phone with Vince and I am going to recheck the plug wire sequence (for the 100th time), make sure my dampener's top dead center mark is actually top dead center, and do a compression check.

Any thoughts?

I am going home to do some testing now. I will re-post after I find out more.

I totally agree with the "new" carb does not mean it's bolt on and go...Every new holly I have purchased needed some adjusting.

If it it's dripping fuel, I would check the level of the floats first...also if it is cutting out at about 2500 rpms, the secondary bowl level may need to come up.

You should have a screw on the side of each bowl... on the primary bowl(toward the bow)remove the screw and see if fuel runs out...it should be right at the bottom of the screw hole and not running out...check the secondary bowl too.
Keep in mind the other adustments that others have mentioned are all part of the correct set up.
Good luck!

First, 79nautique, I am on Lake Minnetonka in Minnesota (about 15 minutes west of Minneapolis).

Second, I fixed the problem and am embarassed to admit what the problem was because it something we have battled a couple of times. The plug wires for 6 and 8 were swapped. This happened when a friend of mine helped me pull the plugs out after it flooded last weekend. I definitely would have checked this sooner, but I was under the impression that the engine would backfire and not start if the plug wire sequence was wrong. Well I know that is not true and will never let this happen again.

It is now running pretty well. I still have a couple questions.

1. So 79nautique and GottaSki, are you telling me I should be able to go from dead idle to full throttle and it should just jump out of the water? It does not really dog on me but if I just hit it, it just does not pop out the water as fast as I thought it would. This is my first Correct Craft but I have driven other inboards. I figured with the 454, this should fly out of the water when you hit it.

2. It is still starting hard and I am not sure if it is flooding (I do not smell gas and it runs fine once it is going). The leaking carb problem has stopped (I am assuming that was related to the plug wire problem). I am thinking about adjusting the thermostatic choke and resetting my idle mix adjustment screws back to 1.5 (currently at 2.5).

Any thoughts?

Thank you to all who have responded. This is a great forum.

GottaSki, I had a 13" x 16P 4 blade on there which I swapped out for a factory recommended 13" x 12.5P because I could not get my RPMs up to 4400 and it would move to fast at idle. Speaking of the 425HP, have you or anyone else ever seen one of those in a Martinique? That is what I wanted but could not find one anywhere.

The Mallory distributor I have is brand new so I doubt anything is worn or broken. Is there another adjustment I should make on the distributor other than adjusting my initial timing?

How do I know what size primary power valve I have? This carb should be setup the exact same as the original carb that came with the boat, according to PCM and SKIDIM, and the manual says 85 for the Power Valve.

What does WOT stand for (wide open ___?). I am not sure about cutting away the threads. I am also not sure what the plug insulater is. Do I disable to secondaries by having someone manually restrict them?

Thanks again.

WOT...Wide open throttle!

Your prop should be good for hole shot with 12.5 pitch...the lower the pitch = quicker out of the hole...higher pitch better top end speed.

As far as what to expect for hole shot...if pulling a slalom skier(ave wieght) out of the water...your boat should almost yank his arms off if you hit it wide open. So...it should pretty much jump up and get on plane fast!

Scott,

Where do you live? If your around Central Florida I have an 87 Martinique with a 351. Be happy to meet up and do a side by side.

I'm sure yours will wlak mine outof the hole, but you'd get a good comparison. I also have an 89 SN with the 1.23:1PCM tranny. Much better whole shot than my Martinique. I like driving the SN better but the family still likes the Martinique the best.

Tim

Tim:

Thanks for the offer. I can hopefully find someone around here to do hole shot test against.

Thanks.

Scott

I am no expert but I do know SEVERAL top car guys adjusted my carb and it was just OK.... I found as ex PCM mach., he spent about 20 minutes in it and it ran better than the day I got it. That was 7 years ago. After sitting up for 5 years it started the second time I turned the key.