1989 Johnson 150 hp has spark, but will not fire.

[Caudfish15]

I've recently bought this boat and the motor ran great the first three days, besides some wavering at full throttle. I repaired a small broken hose that was spitting fuel, then it continued the wavering. Later, it began running horribly at idle and proceeded to the point where it wouldn't fire up. I took it to a mechanic and he noticed the VRO pump was leaking fuel so he replaced it with a regular fuel pump. Expecting my problems to be fixed, now the motor cranks, but will not fire up. The compression was all at 80 except there was a 85 and 83. The mechanic says that's good compression for that motor. He continued to work to find out why it wouldn't run, but was ultimately stumped. I changed the spark plugs and confirmed that all six cylinders were getting spark, but couldn't get the thing to fire up. The mechanic recommends cleaning up the carbs and checking the reed valves. I'm not quite convinced that he is right about it not firing up because of the carbs. The best thing that the motor did was fire up at the turn of the key and idle really well. Any advise on where I should be going with this motor now? Is the mechanic accurate with his assumption that the reed valves would stop it from firing up or should I be looking into the new fuel pump that he installed?

 

[racerone]

Checked the flywheel key ??

 

[emdsapmgr]

Not sure just what sort of fuel pump was replaced. It comes with a single VRO pump from the factory. You say it was repl with a "regular" fuel pump. What is that? Does it look like a VRO pump, but just without the oil pump? Did he replace the VRO with one of the older (small) 1983 premix fuel pumps? Problem with that is, that when converting back to the 83 style, you must install two of them to compensate for the original single VRO. So the question is-just what pump is on the engine?

 

[James R]

Emdsapmgr is right. Wont run with one standard pump. Quick test to see if it is a fuel problem. Take the air box cover off. Fill a spray bottle with 50:1 mix. Dont forget to have water going to the water pump. Have someone turn the motor over while you spray fuel into the carb throats. If it fires fuel supply is the problem.

 

[boobie]

Will the spark jump a 7/16" open air gap on a spark tester when cranking ??

 

[Caudfish15]

Thanks for the input! I'll bet you guys are right about the duel fuel pump. I haven't tried putting gas into the carbs, but the mechanic who has it now said the same thing about needing two standard fuel pumps. I just can't believe that the other mechanic didn't know anything about that. He said it was going to be an older style fuel pump and he's done it several times before. He ordered a sierra model, but I can't find the model number for the one he put on. I'm hoping this other mechanic gets to it tomorrow. He's always backed up because he has a good reputation. I'll be sure to update you guys when I hear something. Hopefully that's the only issue causing it not to start because we did some troubleshooting and everything checked out as far as putting out and receiving power. I definitely need to learn more about it so I can stay away from spending so much money.

Not real sure what you mean about the spark jump? We had a spark light tester which showed spark on all six cylinders at the same time.

 

[emdsapmgr]

A couple of things you need to check. When the engine is running, shut it off and check the plugs. Are they all wet, all dry? All look the same? Wet plugs mean it's getting fuel but may have weak/no spark. Dry plugs may mean the ignition is firing, but there is no gas. Also, when running, to a cyl-drop test. Pull one plugwire off and see if the engine rpm's go down slightly. It should, as the engine would only be firing on 5 cyls. Do each plug and see if they all react the same. If you pull the plugwire off one plug and nothing happens, then it's not been firing at all. What did you find when you checked the flywheel key: If it shears, the flywheel will be out of time and it won't run at all right. That engine will seem to run just fine at idle when sitting on the trailer. You can't tell if it's running on 3 or 6 cyls when idling on the trailer. You need to put a load on it: in gear, in the lake in order to see if it' firing on all 6.

 

[Caudfish15]

Well guys, I finally got my boat back today. The mechanic said it wasn't starting because of a sheared flywheel key (emdsapmgr). He replaced that and said it was running fine in the shop, but couldn't lake test it until Monday. He did say that he had trouble getting spark on cylinder #1 at first, but when he moved some wires around while checking everything out the spark came back on all 6 cylinders. He said the choke (kill switch) on the motor was also turned out of place, but he set everything where it needs to be. Not wanting to wait until Monday for him to lake test it, I picked it up and took out on the water. Took off great, but after running a little ways began missing at full throttle, as it did before hand, then I lost power on a cylinder. I'm guessing that was what he was having trouble with at first too. He did say it may do that as well and he suspects the power pack. I called him to explain how it was running and he said it may not be a power pack issue, could also be some wiring. He said I could take it back to him, but he wouldn't tell me when he could get to it. I really want this boat running well by next week, so what do you guys think might be happening? Power pack would cost $260 from that mechanic, but I did see some online for less. This being my first boat, I don't want to keep throwing money into it, but I do want it to run consistent. I road around to fish a bit today and at times it would open up on all 6, but then would lose a cylinder again. Advice would be greatly appreciated.

 

[emdsapmgr]

Heat is the enemy of a weak ignition component. Weak components run fine when cold, but begin to crap out when the engine finally gets up to normal running temps. Possible your do have some ignition component that is failing after the engine has run a bit. I'd probably do a cyl-drop test. Pull each plugwire off a plug-one at a time and see what happens. The disconnected plug should cause the engine to drop rpm's on each good-firing plug. If you pull one plugwire off and nothing happens-then that plug likely is not firing and is not contributing to running the engine. That starts to give you an idea of where to start looking. You could even have a bad plugwire that is jumping to ground as the engine warms up.

 

[Caudfish15]

Hey thanks for the input guys. I haven't been able to do a cyl-drop test, but I do know it's losing a cylinder. I asked the mechanic if it could be a spark plug wire and he said they looked fine when he checked them. I'm going to order a powerpack online today. Sierra and CDI seem to be more in my price range, a few people have given mixed opinions on CDI electronics. Do you guys have issues with CDI electronics? Any preference sierra or CDI? I wish I didn't wait so late in the week to order, but I've been busy. Also, does it hurt to continue to run the motor while I'm waiting for the power pack? It's running pretty well around 40mph, but has a miss around 50-55 mph.

 

[emdsapmgr]

An occasional miss at high rpm's could be a faulty spark plug wire. If you'll notice, these wires coil around the plug, the actual coil. When they get old, possible for the plugwire to spark direct to ground-causing your miss. Might want to run your engine on the trailer after dark. See if you can see any flashes to ground from each plugwire.

 

[Caudfish15]

I've been out of town for a couple weeks, but I have replaced the power pack. The motor sounds like it's stronger, but still has the loss of RPM's at WOT. After checking things out I replaced 2 more coils. That makes 3 new coils, but they had to order more. I tried looking for spark on the water at night, but couldn't see anything. Would I have to be running it wide open and watch or will be able to see it while idling? Is there a chance that it's not getting fuel at WOT? If so, do I look into the carbs?