1985 85 hp fuel problems

[intel*outside]

Re: 1985 85 hp fuel problems

1. I am almost certain that I did. If this makes any sense:
(a) outlet check valve
(b) valve held by two screws
(c) other valve removed w/ pin punch

set 1&3 back with a socket around the rim

(a)\_/(b)\_/(c)/^\

2. yes - the tank is internal. The tank was empty when I filled it with clean gas though.

Here is a little history on the boat -
The week after I picked it up, I got it out on the lake. Ran fine for a good 30min then it just died on me. I was able to limp it back to the ramp after a tow and waiting for a while with the cover off and the o/b up. I called the guy up who sold it to me "lake ready" and he came over to my house, pulled off the carbs, cleaned them out, and we noticed that the fuel going to the filter was milky, which was an indicator of water in the fuel. This boat had also been sitting since last season and had the old fuel in it. Some of the bad fuel was pumped out, treated with octane and seafoam, and then I went to try again the next week.

Same issue - couldn't even get it out 30ft before it died. I looked at it again and the mixture was still milky after putting some new gas in (there was still some of the old gas remaining). I pumped that out using the primer bulb and still had the same issue with no power. Next, I pulled off the the inline filter and rigged a direct line to the primer bulb, and with modest pumping, it got us around just fine. If it would die, pulling the motor up and letting it fall a few times, and then pumping the bulb would get it running again, leading me to think something was sticking internally or water/fuel flooding the carbs.

Next time I got out, it ran good for the first 30min, gave me trouble for the next few hours (no power and engine dying), gas was clean, then ran amazing after it died one time, I pulled the cover off, waited a few min, and gave it a some pumps. After that, it needed no more pumping and ran like a champ for the rest of the night.

For some reason, I thought it would be good idea to put the inline fuel filter back on after the fuel pump rebuild, because I thought that the problem was with the check valves, but as soon as I got on the water there was no power and pulling off that filter did not help so I think it may be possible that something was dislodged.

Here are the parts I ordered:
21-F177330 Valve-Check, Mercury - Mercruiser 21-F177330 3 $5.50 $16.50

SIE-18-7806 Fuel Pump Kit 1 $5.59 $5.59

Are they the correct ones?

More info -
Would Gasohol have that effect with new gas? Actually - now that I think about it, I did put in 3 gallons from a gas can that was on the boat from the last run. Wonder if that could have had some impact? It was only 2 weeks old. Would it be practical to bypass the fuel pump completely to see if that solves the issue? Thought it also could be exhaust seeping in, so ran the motor without the cover (I know - not the best idea) and that didn't solve the problem.

I know this is a lot to digest - thanks again!

 

[john from md]

Re: 1985 85 hp fuel problems

The parts appear to be correct and the check valves seem to be correctly installed.

If you had someone pumping the ball slowly would that keep the engine running? When it quits, does it start right up?

The next time you try it, when it quits, crack open the carb fuel bowl nuts over a rag and see if one or more of the carbs is not getting fuel. Even though the guy cleaned the carbs, they could still have sticking floats. That is the only thing that could possibly be dislogged by dropping the engine on its mount.

BTW, this engine weights 225 pounds. It is not a good idea to keep dropping it on the mount as it will crack.

John

 

[intel*outside]

Re: 1985 85 hp fuel problems

The last time it was out, shaking the motor did not have the same effect as the previous outings. You do have a good point and I will not being doing that anymore. The engine ran with the throttle 3/4 open, but at a snails pace. Pumping the bulb didn't seem to help at all. When I opened it up all the way, the engine would just conk out. It fires right back up after it dies, but still no power.

It would usually start off with plenty of power for the 1st 15-30min and then start acting up, but this time it happened right from the get go.

 

[john from md]

Re: 1985 85 hp fuel problems

Are you sure that all three cylinders are firing? When it is running, pull one wire off at a time (at idle) and see if you find one that doesn't make a difference.

John

 

[intel*outside]

Re: 1985 85 hp fuel problems

I'll give that a shot and post back - thx.

 

[intel*outside]

Re: 1985 85 hp fuel problems

Hey John - reporting back.

I pulled the carbs and fuel line apart and went over them with a fine tooth comb, cleaning every bit of gunk out that I could find. Next I tested the newly rebuilt fuel pump by cranking the motor a few times with the carbs off. The fuel pulsed out at the line closest to the carbs with no problems. I then pulled the plugs, which were pretty fouled out and replaced them w/ NGK BUHX. I then brought the boat to the launch, got it off the ramp, and it still had no power, so I idled over to the nearest cove, removed the cover and pulled the plug wires one at a time. The motor died as soon as the top and bottom were pulled, but the middle one did not make any difference. When that one was pulled, the motor kept running. The top wire gave me a little shock when pulling it. I tried to test for a spark on each line with a screwdriver, but perhaps I wasn't doing it correctly because I couldn't produce one for any of the wires.

So - I don't think this is a fuel or air issue (let's hope not mechanical), which leaves just the electrical. Could you point me to a link or provide any info that could help me further narrow down the problem on the middle cylinder? Perhaps a bad coil? I'm am far from a mechanic and just trying to TS with common sense and direction.

Thanks for all the help so far! You are an invaluable asset to the boating community and I really appreciate your insight.

 

[john from md]

Re: 1985 85 hp fuel problems

To test for a bad coil, switch coils with one of the others. In order to test the spark without running, do the following.

Go to Radio Shack and buy a set of the jumper wires that have colored wires and alligator clips on both ends. Get the smallest sized they have. You will need five jumpers.

Pull the plugs and re-connect the plug wires to them. Take three of the jumpers and connect them to the ground on the block under the coil rack. Take the other ends and sqeeze one side into the area between the plug shell and the crush washer. Do this for each plug and then position them so you can see them fire from the left side of the engine. Next take a jumper and jump the neutral interlock switch on the right side of the engine.
Turn the key to the on position.

Now, standing on the left side of the engine, connect one side of a jumper wire to the small stud on the outboard side of the starter solinoid. Then next step will spin the engine so prepare yourself and step back a little.

Touch the other end of the jumper to the top of the forward most large stud on the solinoid. It will spark but it is low current draw and won't hurt anything. What you are doing is energizing the starter the same as if you turned the key. I have made a jumper to do this but I work on a few engines.

Look for plenty of blue sparks on the plug electrodes. If the problem has moved, you have a bad coil. If it does not, you probably have a bad CDI box or trigger.

To test for this, swap the two CDI units. The rear unit has an extra circuit as it used on four cylinder engines also. Make sure that when you swap the CDI units, you use the Orange wire connection for the #3 cylinder as the Red wire may be dead.

If it runs ok like this you are set. If you still have a dead number two cylinder, you have a bad wire or bad trigger.

Keep me posted.

John

 

[jason32038]

Re: 1985 85 hp fuel problems

WARNING!!! If you touch the plug wires with the engine running you WILL get shocked. You can pull them off with INSULATED pliers. Remember rubber handles doesnt mean that they are insulated. It's safer to note how the engine runs then shut it down...take off one plug wire and fire it back up and take note of how it runs. If you dont notice a difference of how the engine runs when removing a plug wire you know the cylinder is dead or you have a blown head gasket.

 

[intel*outside]

Re: 1985 85 hp fuel problems

I was able to get it out this past weekend. I found that I had pinched one of the coil wires (a blue one) in the fuel pump housing when I put it back together. After taking the wire out, I was able to get fire on all three cylinders. I didn't switch out the coil or the CD module yet because I thought it was good to go. The thing is, it seems like it will run strong for the first minute or so and then one of the cylinders just conks out. I seems to do better with only me in the boat, but runs in trouble a lot more quickly under load. I'm going to swap around the CD module this weekend and see if that does the trick. I'm keeping an eye out for a new ignition system on ebay....

 

[sho3boater]

Re: 1985 85 hp fuel problems

If you go to a place like autozone, you can buy a spark tester for like $5 or so. I use one all the time to test spark, you put the wire on it and can screw the stud in/out to determine how far it will jump. Most will jump over 3/8" on one. I just put one wire in it and fire it on a hose, turn off and do again for next plug.

 

[intel*outside]

Re: 1985 85 hp fuel problems

good idea - that should make testing the spark a bit easier.

 

[jason32038]

Re: 1985 85 hp fuel problems

I was able to get it out this past weekend. I found that I had pinched one of the coil wires (a blue one) in the fuel pump housing when I put it back together. After taking the wire out, I was able to get fire on all three cylinders. I didn't switch out the coil or the CD module yet because I thought it was good to go. The thing is, it seems like it will run strong for the first minute or so and then one of the cylinders just conks out. I seems to do better with only me in the boat, but runs in trouble a lot more quickly under load. I'm going to swap around the CD module this weekend and see if that does the trick. I'm keeping an eye out for a new ignition system on ebay....

Clean or replace your plugs. There could be a fouled plug on the cylinder that wasnt firing before. Also if you havent taped up the wire that was pinched there is a possibility that it is still grounding on the engine. Check connectors on control panel one could have came out of the crimp connector like mine had.

 

[intel*outside]

Re: 1985 85 hp fuel problems

I got a chance to go out to the drydock on Sunday to bake in the sun and work on the boat. I think I was mistaken on the cylinder with the problem because I tried starting the motor with only one plug on at a time. The engine would turn over and run when only the middle or bottom were attached, but would turn over and die with the top. I replaced the top coil with a known good and still had the same issue, so I guess I can rule out the coils. Next I swapped the wiring on the cd modules to the coils and swapped the wiring for the cd modules at the patch panel. Now top or middle would fire up the motor and run separately, but # 3 would not even turn over on the red or orange. My best guess at this point is that the cd module is fried. I triple checked my wiring, so that is not the issue. Would this indicate a bad cd or bad trigger?

Thanks

 

[john from md]

Re: 1985 85 hp fuel problems

Bad CD module would be my best guess. You have done almost as much troubleshooting as you can. Since it moved when you switched module plugs, I believe the module would be at fault.

John

 

[intel*outside]

Re: 1985 85 hp fuel problems

Bummer - new CD module didn't fix it. It will idle on each cylinder by itself, and was running a little better, but as soon as you get on it, it bogs down and dies. what next, the trigger???

 

[intel*outside]

Re: 1985 85 hp fuel problems

Throwing in the towel and bringing it to a mechanic... I'm stumped.