1988 mercury xr4 150

[winnerbassboat]

Ok so me and my son is running down the river in our boat and pop a loud noise and a shake almost like hitting a log. Now the engine will not start and has no fire, has good compression on all six cylinders. Anybody got any ideas, engine was rebuilt 3 years a
go.

 

[CharlieB]

Re: 1988 mercury xr4 150

Was the prop dinged by contacting a log?

Did you check for spark on all cyls?

Check WOT timing.

If you still have spark but the WOT timing is no longer correct, pull the flywheel and check the flywheel key, it may be sheared, shifting the timing out of range far enough the motor will not run.

 

[SparkieBoat]

Re: 1988 mercury xr4 150

links for a cheap dva adapter and a free troubleshooting guide are in my sig below.

 

[winnerbassboat]

Re: 1988 mercury xr4 150

Was the prop dinged by contacting a log?

Did you check for spark on all cyls?

Check WOT timing.

If you still have spark but the WOT timing is no longer correct, pull the flywheel and check the flywheel key, it may be sheared, shifting the timing out of range far enough the motor will not run.

no ding in prop and didn't hit anything, the boat had been running good all day and after fishing for about 3 hours it started up like new but about two minutes after we plained off it made a pop nose similar to two pieces of metal hitting together and shook really bad { thought at first the motor had fell off } But it has no spark on any cylinder and seems to be turning over slower than normal even after charging battery all night. Good compression but the key you talk about in the fly wheel i took the fly wheel off thinking maybe it broke causing the pop but it looks fine, i dont see a key, is it similar to the key in say a lawn mower?

 

[Chris1956]

Re: 1988 mercury xr4 150

There are some ign troubleshooting procedures on the CDOElectronics web site. That motor should have the six coil ADI ignition system. The procedures will help you determine is the stator is bad or the trigger is bad, or the switchboxes are bad. Of course it could be the wiring between them.

 

[gwukena]

Re: 1988 mercury xr4 150

Don't think those engines had a flywheel key, used master splines on crank. Possible flywheel magnets have come loose contacting stator, another issue that sometimes happens is upper crank bearing goes for a chit and flywheel hits stator. Can you bar it over easily enough by hand?

 

[winnerbassboat]

Re: 1988 mercury xr4 150

Was the prop dinged by contacting a log?

Did you check for spark on all cyls?

Check WOT timing.

If you still have spark but the WOT timing is no longer correct, pull the flywheel and check the flywheel key, it may be sheared, shifting the timing out of range far enough the motor will not run.

Ok just got home and looked at it, left the motor trimmed down last night and now I see black oil leaking from around the prob, did the motor blow and still have 130 psi on all six cylinders and can turn the engine over by hand with a little effort

 

[Chris1956]

Re: 1988 mercury xr4 150

If the engine can be turned over hand, and has good even compression on all six, the powerhead is likely good. The black oil is likely gear oil or residual 2 cycle oil from unburned fuel.

 

[CharlieB]

Re: 1988 mercury xr4 150

Inspect that flywheel, shaft and stator.

Some models did use a spline, other a key similiar to a lawn mower.

As another poster mentioned, look inside the flywheel at the magnets, are any loose, broken, or show any 'rub' marks where they have touched the stator?

Inspect the outside of the stator, are there any contact marks anywhere?

No spark cranking? Disconnect the Black wire with the thin Yellow trace that connects both ignition switchboxes to the motor wiring harness and retest for spark.

Repost all your findings, we'll get this figured out.

Check the links in Sparkie's signature, follow the directions, guaranteed you will find the answer.

 

[winnerbassboat]

Re: 1988 mercury xr4 150

ok pulled fly wheel did not see any broke or loose magnets on fly wheel, the stator has a rub mark on the top of it and a red wire is slightly exsposed dont see how the fly wheel could rub the top of the stator but guess it did, side of stator looks normal, unhooked the black wires with yellow stripes and made no difference. so if the fly wheel rubbed the top of the stator would it make the loud pop that it made and the shaking, also what would cause the fly wheel to rub the top of the stator?

 

[CharlieB]

Re: 1988 mercury xr4 150

Good pictures of the marks could help.

Are there corresponding marks inside the flywheel?

Is the flywheel splined or keyed?

Have you done a cranking spark test?

What did you find?

Have you checked WOT timing?

 

[SparkieBoat]

Re: 1988 mercury xr4 150

you need to do the test to figure out what is wrong. hard to figure just by looking at the motor, some problems can be visually seen, but you have to do the regular test to figure out what is wrong. see post #3

 

[Faztbullet]

Re: 1988 mercury xr4 150

See if flywheel has a lot of slop as it sounds like upper bearing failed... What years used a key as I have never see a 2.0/2.4 2.5 with a keyed crank..

 

[winnerbassboat]

Re: 1988 mercury xr4 150

ok was told it is the trigger and the stator so my question is how to get the trigger off, the stator just unbolts with allen heads but then there is a round plate that the fly wheel bolted to that keeps me from removing the trigger, do i need a puller to remove it, it is splined

 

[SparkieBoat]

Re: 1988 mercury xr4 150

I would go ahead and get new switch boxes also..I assume you checked that crankshaft bearing that was mentioned earlier?? hate to see you put those new parts on just to have them blown again.

 

[travisb5470]

Re: 1988 mercury xr4 150

ok was told it is the trigger and the stator so my question is how to get the trigger off, the stator just unbolts with allen heads but then there is a round plate that the fly wheel bolted to that keeps me from removing the trigger, do i need a puller to remove it, it is splined

I'm having the same no spark problem. What was wrong? I'm thinking of replacing the stator and trigger to. This motor is just so old. I'm thinking it's the problem.

 

[quicktach]

Re: 1988 mercury xr4 150

I may have missed an answer, but can the motor be turned over relatively easy by hand. You say it's cranking over slower even with a good battery charge. I suspect a mechanical break or failure ... con rod or bearing. What is the motor serial # ?

 

[wired247]

Re: 1988 mercury xr4 150

I'm having the same no spark problem. What was wrong? I'm thinking of replacing the stator and trigger to. This motor is just so old. I'm thinking it's the problem.

Rather than resurrecting a 2 year old thread with your problem its probably better to start a new thread detailing your issues.

 

[winnerbassboat]

Re: 1988 mercury xr4 150

Update, replaced starter that was the slow turn over problem, and replaced trigger, stator, and both switch boxes, $500 later she runs like new

 

[CharlieB]

Re: 1988 mercury xr4 150

Thanks for posting the follow up.

We would have keep at it trying to help. Electrical parts get spendy, fast.

There is a minimum cranking speed of 300 RPM necessary to generate enough stator voltage for the ignition system to function. Your old parts may still be good IF you replaced them before replacing the starter. So if you haven't tossed them, save them, just in case you need them. There IS bench tests other than just an Ohm meter that can be used to determine if they are good or bad. But not for the switchboxes, only the stator and trigger. If I remember correctly Faztbullet has a schematic that details Ohms test for switchboxes that is a pretty good indicator. I should have copied and saved it.

Glad you got it working and on the water again.

I'll have to check the forum to see if Travis posted his problem.