Evinrude 150HP 1991 power head hesitates going from idle to WOT

[bmontini]

Hello.

First, great forums, I have been reading non-stop for several days now, but I can't single out my issue. [colour=RED]Sorry for the length of this posting, but I figured for troubleshooting, I should be as detailed as possible[/colour].

I recently inherited a 1979 19' Glastron with a rebuilt powerhead/motor (I was told that the "motor" was 1991) Evinrude 150HP V6 w/ VRO. The boat dealer asked me if it was the "small" or "large" motor, and we decided it was "large" (see 2nd issue below for why we don't know what model it is) Running 89 octane, fresh tank. Evinrude/Johnson TC-W3 in oil resivoir. It is using gas (lots!) and running through about half the resivoir every 70 gallons or so)

1st issue
Ran the boat 6 times this summer after we got it in July.

Performance to date:
-It is a little slow to startup, but not bad
-on rare occasion, it would hesitate going from idle to WOT (with or without a load (skier, etc)) but basically ran like a champ! (though a little "stinky"/gas fumes on idle)

Before my 5th trip out, I replaced all of the plugs with exactly what the rebuilder recommended Champion L77JC4 gapped to .040. ENGINE RAN PERFECT, (6 people in the boat too!) Less Stink, no hesitation, but on our hummingbird fish/depth finder, it alarmed a few times to "over-voltage"

Went out last weekend, The boat was a little slow to start, but otherwise OK at idle. Maybe a small "clanky" sound that I don't know if I heard before. Maybe missing 1 or 2 cylinders (rarely). Took off down the lake. Running great at around 4500RPM (not maxed out on throttle) and it just dies. Sounded like it ran out of fuel. Took about 6 seconds to go from 4500 to 0 rpm. Turned off key, tried to start. Nothing but "click-click". Picked up the motor to see if anything around prop.... nothing. Put it back down, starts right up and off we go.

The big problem. 30% of the time with 2 people in the boat, no skier, 90% of the time with 1 in the boat and 1 skier that I went idle to WOT, it would hesitate and want to die (and sometimes did die). Recovered by pulling back the trottle near or to idle. Try again. usually on the 2nd or 3rd push to WOT it would grab and run perfect. Fast and powerful.

Got home, did some troubleshooting, keep in mind that I am new to outboard motors!

-all passenger (port) side plugs are a little wet with oil, top driver (starboard) side is wet with oil. Bottom 2 starboard plugs, nice and tan and dry.
-Replaced fuel bulb, old one never seemed to get hard. New one, does but only on every 4-5 pumps. (soft, soft, soft, hard, Soft soft soft soft hard). Hmmmm, any ideas?
-Fuel filter, pulled it, saw a couple of bits of stuff in it, but very little debris, so reconnected.
- tested compression. Cold engine (after reading here, I think it should have been warm first) but 79-80psi on all cylinders except for bottom passenger (port) side 69PSI.
-Tested for spark on all cylinders by warming it up and then pulling 1 boot at a time. All cylinders when pulled dropped motor maybe 200rpm. The lower compression cylinder (bottom passenger) when pulled almost killed the engine, maybe 500+rpm drop) Nobody can tell me why this happens.?????

Every time a plug wire was pulled it arced from the coil spark plug wire boot to the input from the power pack boot on the coil. I definately saw good spark on each, but should it arc so violently?

Checked battery voltage at idle (13.5V) and a higher RPM (13.7V) Seems like the regulator/rectifier is working. (at least I think it is according to that test, if I am wrong let me know)

Please help! I am stuck and frustrated!


- 2nd - please help me find the model/serial number! It is NOT on the mount/tilt/trim mechanism. It is just all "paint"! I can't find anywhere that the rebuilder painted over the tag, but is there any other way to tell what model powerhead I have? 2 power packs, 1 rectifier/regulator (10Amp). Help!


Thank you so much for your help in advance, I am frustrated and don't have a ton of money to trow at this right now.

Brian

 

[Joe Reeves]

Re: Evinrude 150HP 1991 power head hesitates going from idle to WOT

Most models up to around 1989 had the model and serial numbers on a plate, attached to the port transom bracket.

Later models has a heavy duty decal of sorts (what idiot thought that up?) pasted to the top inside of the swivel bracket (bkt that the engine swivels/turns on). It is usually located on the top port side, facing the engine's exhaust housing (hsg between the powerhead and lower unit).

The fact that the engine will at times hit full power and stay there as per your statement of "Try again. usually on the 2nd or 3rd push to WOT it would grab and run perfect. Fast and powerful" eliminates any possible carburetor problems as carburetors do not come and go. They are either okay or fouled.

However, you mentioned that the appearance of certain s/plugs varied. The compression you quoted wasn't impressive. It should have a minium reading on all cylinders of 90 psi. Try another gauge.

Yes, the spark is violent.... to pick a round figure, about 50,000 volts. Enough to knock one out of the boat. With the plugs removed, the spark should jump a 7/16" gap on all cylinders with a strong blue lightning like flame.... a real SNAP! Does it?

Possibly that spark is intermitent? Check the stator under the flywheel. The two large black coils at the rear of the stator provide approximately 300 AC volts to the powerpack capcitor in order to energize the ignition. If those coils are leaking down a sticky substance on the timer base and powerhead area, that would cause a voltage drop to the pack. If this is the case, replace the stator.

You state that replacing the s/plugs resulted in improved performance for a time. A failing stator would cause a engine to act like that.

The pumping the fuel bulb problem...... that sounds like the anti siphon valve which would be the fitting which is located right where the rubber fuel hose attaches to the built in fuel tank is either non-existent or stuck open. This would be an aluminum fitting, about 4" long and would have a ball valve, seat, and spring within it. If this unit does not exist, it is possible for the fuel from the engine to siphon backwards into the tank due to the fact that the tank is the lowest unit. Result..... every time you pumped the fuel bulb, you would be starting from scratch.

When this problem arises, if you haven't tried pumping the fuel primer bulb (acting as a manual fuel pump) to see what effect that action has, do so. Let us know what you find.

 

[bmontini]

Re: Evinrude 150HP 1991 power head hesitates going from idle to WOT

Thanks for the great response. I certainly appreciate it.

Ok, no serial number ANYWHERE, the guy must have took it off after he rebuilt it. (DANG!)

So I took it into a Evinrude dealer for service. He tested 96, 96, 95, 97, 100, 86 PSI. He said one was a bit low, but probably due to the high level of carbon in the cylinders. Recommended OMC "engine flush"(??? I think)

BIG SPARK, good jump. no problems there...

Here is what they said after "diagnosis" today. Your feedback is welcome...

1 - Heavy cylinder deposits, recommend running them with some sort of additive after I get it back.
2 - Leak in the fuel system. Noteably in the fuel scavenging system (seemed to be his #1 problem). Cracked areas to be fixed. He said that this will prevent proper back-pressure and cause the system to run heavy oil (i think!) Check valves were "outdated" and not working properly. (i think this was on the VRO) and should have been replaced when it was rebuilt. He said the reason it was so $$$$ was labor to remove carbs, etc....

3- Said the plugs were wrong. we were told by the engine builder that L77JV4 champions were proper, he said NO. He said that I had a 1986 150 GT motor and this was not correct. Some parts (carbs, etc) were from 1988/89, but not 1991. He told me another champion # which I can not remember.

He said ignitition system looked strong according to his tests.

He also said that I needed a few various parts (most expesive part was 19 bucks) but in total it was going to cost 725 to fix. (including diagnosis time) EEEKS! I asked him on a scale of 1-10 to tell me how certain he was that this would fix it. He said 80%. He would know for sure after running it on the dyno

What do you think of his diagnosis??

 

[Joe Reeves]

Re: Evinrude 150HP 1991 power head hesitates going from idle to WOT

Bad check valves, which are actually called fuel recirculating valves are located in the intake manifold, in back of the carburetors. A faulty recirculating valve will cause one cylinder to run lean with the related cylinder on the other end of the small recirculating hose to run rich.

Leak in the fuel system..... cracked areas? I have no idea what that might be. However, it sounds like your mechanic is giving you the straight scoop.

I prefer Champion QL77JC4 plugs, gapped at .040 but I'm not aware (at the moment) as to exactly what plugs your engine calls for.

 

[emdsapmgr]

Re: Evinrude 150HP 1991 power head hesitates going from idle to WOT

For starters, we can help you if we know what engine you actually have. There is a model number on the block which will tell what the engine is. On the top of the block, on the flat part of the port cylinder, there is a quarter-sized round welch plug. The model is stamped there. You may have to scrape the paint off to see the lettering. Possible you have a mixture of parts from various years on the engine. Compression is not bad, just slightly low on the one cyl. You could have a lot of carbon build up, esp if you are burning a lot of oil, or one side is running cold. I would run a can of BRP Engine Tuner through it and then see what the compression is after you are done.

 

[bmontini]

Re: Evinrude 150HP 1991 power head hesitates going from idle to WOT

I will do that when I get it back. The dealer said that there is a mish-mash of parts, but the main unit is a 1986 Evinrude 150HP GT. I will get the actual model #

Thanks for everyone's help so far.

Brian