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1989 Force missing at WOT

G

gobster

New member
This is a long post, so bare with me. I have a 1989 Cajun Bass boat that I bought a few months ago with a 1989 Force 150 in the back. When I first bought it, it would run about 48-50mph with just me in the boat. Ran great. It started missing at about 1500 rpms so I checked the timing to see where it was sitting and when I connected my timing light to #1, there was no spark. Thought coil, so I swapped #1 with #2 but still no spark to #1. I downloaded the wiring diagram and pulled the side plate with the coil packs off to see if I had a broken or chaffed wire. Couldn’t find anything. So I started tracing wires per the wiring diagram and found that there were several of the coils that didn’t match the wiring diagram I had. No idea how it was running at all. I rewired everything as per the wiring diagram and had spark back at #1. Timing was good. Did a compression check and the average over the 5 cylinders was 148 PSI with the lowest at 142 and the highest at 153 PSI. Took the boat to the lake to check it out and my miss at about 1500 rpms seemed to be gone. But when I went to WOT, I couldn’t get above about 3800 rpms with out the engine missing again and my top speed was about 32 mph. The max RPMs that I was getting at this point was about 4200. I changed the plugs, pulled the carbs and ran carb cleaner through everything and used my air compressor to blow everything out. When I pulled the carbs, they looked sike they had recently been rebuilt, clean as can be. Re-synced the carbs and adjusted the butterfly's to be horizontal at WOT. Rechecked to make sure timing was set at 30-degrees BTC. Took it out again today and have the same issue. I brought my timing light with me and hooked it up to each cylinder and ran it to WOT to watch the light to see if I had a coil that looked like it may not be firing while at WOT. Checked all 5 cylinders. When I checked the light at about 3500 RPMs, it was a steady light bulb, on all the time. But when I reached about 3800-3900 RPMs, all 5 cylinders seemed to have a slight miss when looking at the light. My RPMs never reached more than about 4200. The engine had a vibration at that point as well. So here is my question, If all 5 cylinders are in fact missing when I go to WOT, what could cause this? Could it be starving for fuel? I’m not a boat mechanic and don’t have a lot of experience with boat engines. I have 24 years of aircraft maintenance so I do have a mechanical background. Just trying to figure out what my next step needs to be to get this back running as it did when I bought it. I know that there isn’t a lot of love for Force motors out there, but that is what I have. If your recommendation is to use it for a anchor and buy a different engine, please don’t reply. But I would appreciate some insight into what I should look for next.
 
outboardignitiondotcom has test procedures for your motor.
Loosing spark on one could be the coil or the stator. Stator test: it can test good but still be bad :).
The coils don't often go bad, I've only seen one bad in 40+ years.
The wires to the trigger are very thin and brittle and the original connection between the wire and the connector can break under the shrink wrap. Gently tug on each wire and see if it comes loose??
 
Jerry - on the wiring diagram for outboardingitiondotcom, it shows the diagram for using the oem trigger and the cdi stator. It shows that their stator only has 4 wires coming from it and requires a jumper wire from #2 to #5. I must have the oem stator as it has 6 wires coming from it. This is probably a dumb question, but do I still need to use a jumper between #2 and #5? It didn't have one when I initially looked at it. I don't want to take the chance of frying something if I put one on now. I appreciate your help.
 
Thanks Jerry. I found a wire for #5 from the stator that appeared to be broken so I replaced the terminal. Took it out again today to see if that was the issue, but the problem persists. While running it WOT, I watched the engine (as much as I could while still steering the boat) and saw that there was water squirting from the exhaust manifold. It doesn't appear to be doing it at lower RPMS. Is it possible that water could be going into the cylinders at WOT from a bad gasket and causing my problems? Or water going under the flywheel to the trigger and stator and causing the problem? I attached a picture of where the leak is at. Hopefully it shows up. A little difficult to do while driving the boat.
 
Picture of the exhaust leak location
 

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Pull the plugs and inspect.
Had that problem, yet had 145# comp on all 3 cyl. TINY!!! little pin hole in the head gasket causing a miss.
Try tightening the bolts closest to the leak??? Not helping? Then pull the head and replace the gasket.
Salt water motor? Head removal can be very difficult. Bolts seizing and breaking off :(
 
The saga continues. I ordered kits to rebuild the fuel pumps and found that one of the pumps diaphragms had a tear in it. Previously, I had pulled the carbs and pulled them apart and ran carb cleaner through everything. Took the boat out this afternoon and the original problem seems to be fixed with the replacement of the diaphragms in the fuel pumps. Now, my bottom carburetor is dumping gas when at WOT at the main valve. You can watch it coming in at the main valve. The other 2 carbs are functioning fine. I pulled the carb and everything looks to be ok. Ran some more carb cleaner through it but still have the same problem. Could float level cause this? The float is setting level with the bowl when held upside down.
 
Yes sounds like the float is not right.
Is it the brass floats? Check for fuel in the float.
Check the needle for grooves or scoring?
Is it the solid needle or rubber tipped?
The solid needle: the seat can be ripped or missing. Carb cleaners and soaks can damage the seat.
The rubber tipped needle: the tip can be damaged or even missing.
 
The more that I do makes me feel like a dog chasing it's tail. I had stopped getting spark on #5, so I ohm checked the stator and didn't have any resistance on 5 and 6 (the Force stator has 6 wires but only 5 cylinders. #6 just goes to a blank connection). Bought a new-old stock OEM stator off eBay, checked it before I installed it and had resistance for all the wires. Installed it, took it to the lake today and it idles great, started giving it more throttle and it started missing a little. But when I opened it up to full throttle, it ran great. Was running 5500 rpm's again. As long as I was running wide open, it did fine. But when I would try to run at mid level rpm's, it would miss and at one point, it acted like it was going to die. Brought it back home and started checking things again. I still have fire to all 5 cylinders. Started checking ohm's again for the trigger and the stator and once again, no resistance on the stator for 5 and 6. What I don't understand is that I still have good fire to #5 cylinder. Is it possible for the stator to be intermittent in providing power to the blue boxes to fire the plugs? I can't return the stator because the plug for the rectifier was different and I cut off the plug and replaced with one that matched the rectifier. Dumb move on my part, I know. I hate to buy another one but if that what I need to do, I'll do it. Just don't want to spend the money if I don't need to. My next question is what could be causing the windings for 5 and 6 to go bad? Or did I just get a bad stator, even thought it was new. I appreciate the help.
 
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