1984 Johnson 150GT wont come up past about 2K Rpm on load.

[James R]

I have removed the failing VRO and fitted the two fuel pumps necessary. Running on a 3/8 hose and bulb from a small fuel tank through the fill hole eliminating the possibility of fuel starvation from the boat tank. The filter in the motor is clean and the carbs are clean and rebuilt by me. Fuel is flowing freely. Compressions are 95-100. Leak down shows 5psi at 80psi on all cylinders. The cylinders are not scored and have good original cross hatch. Motor idles well and comes up easily off load in the tub. At turn over, with the starter, sparks are good at idle and fully advanced. I have removed and checked the carbs again and they are clean. The motor dies at anything past 2K on load.
Stumped!

 

[Bosunsmate]

Re: 1984 Johnson 150GT wont come up past about 2K Rpm on load.

Too much fuel pressure on old carb floats?
Fuel bulb holding tight with engine off?
Pulled plugs after its died and see what they look like?
Hows it restart after it dies?
Head temp?

 

[Bosunsmate]

Re: 1984 Johnson 150GT wont come up past about 2K Rpm on load.

Primed fuel bulb at 2k to check pump is pumping sufficiently?

 

[racerone]

Re: 1984 Johnson 150GT wont come up past about 2K Rpm on load.

Spark must jump a gap of 7/16" on each cylinder.--That is the proper test for spark !!--Checked the flywheel key ?

 

[boobie]

Re: 1984 Johnson 150GT wont come up past about 2K Rpm on load.

If the flywheel key was sheared, it wouldn't even run!!!!

 

[boobie]

Re: 1984 Johnson 150GT wont come up past about 2K Rpm on load.

Is the timer base free and are you getting full advance ??

 

[racerone]

Re: 1984 Johnson 150GT wont come up past about 2K Rpm on load.

A sheared flywheel key will throw the timing off !!---If the flywheel is not too far out off position it will still run.

 

[boobie]

Re: 1984 Johnson 150GT wont come up past about 2K Rpm on load.

If it's not that far off, he should get more than 2 K out of it !!

 

[emdsapmgr]

Re: 1984 Johnson 150GT wont come up past about 2K Rpm on load.

Recheck for spark after the engine has fully warmed up. Weak ignition components tend to work when cold, can cause misfiring when the engine warms up. (one of the packs could be bad..) It is a good idea to test for fuel starvation: constantly squeeze the hose bulb while at WOT. If the rpm's pick up, it's possible you have a fuel restriction. (bad anti-siphon valve, bad ball valves in the hose bulb, incorrect fuel pumps, etc.) When you had the carbs apart, did you pull all the jets out (idles, mids and high speed-total 3 for each carb throat) and visually inspect them for debris-dried fuel residue? When you replumbed the fuel pumps did you use special factory part-numbered hoses, or just bulk hose? Bulk hose will kink when bent too tightly, causing fuel restrictions. There are 3 special heat-curved factory hoses for that fuel system: 322762, 323401, 324078. These hose part numbers supercede to the following numbers 772572, 323401, 333385.

 

[James R]

Re: 1984 Johnson 150GT wont come up past about 2K Rpm on load.

All of your responses were relevant and I had tried every aspect that you listed. Finally I dug a little deeper and found that I had selected the twin fuel pumps from the 1983 motor not the 1984. The 1984 became a 2.6 needing the bigger upper fuel pump. The lower pump is the same as the 1983 motor. Hopefully this is the answer. We will know soon enough. I am convinced it is a fuel problem as the symptoms are the same as I had on a 150Fastrike when the pump diaphragm was not seated correctly distorting the diaphragm and restricting the action. I will post the result.
Thanks for all the interest and assistance.

 

[boobie]

Re: 1984 Johnson 150GT wont come up past about 2K Rpm on load.

Did you ever check the timer base ??

 

[James R]

Re: 1984 Johnson 150GT wont come up past about 2K Rpm on load.

I did a resistance check and it came out good.

 

[boobie]

Re: 1984 Johnson 150GT wont come up past about 2K Rpm on load.

Is it moving nice and freely and going in it's full range ??

 

[emdsapmgr]

Re: 1984 Johnson 150GT wont come up past about 2K Rpm on load.

Both V6 fuel pumps currently supercede to the same part number fuel pump in the current Bombardier system. The upper pump supercedes to the 438559 pump only. The lower pump supercedes to a kit, part number 393870. That kit should have 1 pc of 438559 fuel pump and a bent (j-looking) fuel hose, part number 772564. That j hose connects the output of the upper pump to the inlet of the lower pump-found on all mid 83 engines and later V6's. Many of these pumps visibly look the same, but do not have the pumping capacity, so getting the correct pump number is vital to fuel flow volume. These later part number pumps are made with rubber components which are resistant to ethanol in the fuel.

 

[James R]

Re: 1984 Johnson 150GT wont come up past about 2K Rpm on load.

emdsapmgr. The pumps I have are both 438559 but the top pump, according to the parts spec for a 2.6, shows a different pump at approx twice the price. I have to assume that this pump has a greater capacity. I have ordered accordingly.

 

[James R]

Re: 1984 Johnson 150GT wont come up past about 2K Rpm on load.

Boobie, everything is moving freely and going full range.

 

[emdsapmgr]

Re: 1984 Johnson 150GT wont come up past about 2K Rpm on load.

I would not think you need the 2.6 pump on that 150. Won't hurt, but was not spec'd for that engine. The 150 engine is the small displacement block compared to the 2.6 and the carbs are probably smaller: 1 5/16" instead of the 2.6 1 3/8" carbs. Yours won't use/need as much fuel. The two later version pumps you currently have should provide more that enough fuel to run well over 2000. There must be something else going on.

 

[James R]

Re: 1984 Johnson 150GT wont come up past about 2K Rpm on load.

Emdsapmgr. The carbs have the aluminum tags and show upper 394741, mid 394742 and lower 394741. Without taking them off again I dont know the throat measurement. You are probably correct as the 2.6 calls for different carbs. This is a GT motor. I don't know if that makes any difference. If it turns out that the fuel pump makes no difference what do you suggest as the next step. Thanks for staying with me on this.

 

[emdsapmgr]

Re: 1984 Johnson 150GT wont come up past about 2K Rpm on load.

I am sure you have checked this, but make sure your timer base will advance all the way to the stop when the throttle is pushed to the WOT position. (check to see if the link arm is still connected between the timer base and the spark advance lever) Also, check that your carb butterflys fully open at that the WOT position. (the carb butterflys must open to where they are parallel to the throat openings-level.) When you had the carbs apart, did you pull all 6 high speed jets out individually and visually inspect them for debris-such as black bits of fuel line hose? It's one thing to run the engine in a tank. That engine can sound fine with 4 or 5 cyls firing. You need all 6 firing when it's in the lake and in forward gear. Have you warmed it up fully and then re-tested all 6 for spark? Weak ignition components tend to work well when cold, but break down once the engine heats up to normal operating temps.

 

[James R]

Re: 1984 Johnson 150GT wont come up past about 2K Rpm on load.

I may have it.
I made some assumptions when I got this motor.I went through it as I usually do and found very little wrong with it. Rebuilt the carbs serviced the lower, checked the sparks. Replaced the old VRO with the two pumps. Incidentally the layout for the pumps that came with the pumps showed the lower pump as the lift pump. The drawing on the parts list shows the upper as the lift pump. Thought that this was the problem so I re-piped according to the parts list. No difference. It ran very well in the tub off load. Put it on a boat and you know what happened.
With your referencing the timer advance, it is free to move and goes all the way to the stop. Sparks are good on test and when I mark the flywheel for each TDC the sparks appear where they should. Advance the timing and the advance occurs.Checked the advance timing position and it showed only 18*. Should be 28*. I have adjusted using the motor off method. Not able to run the motor yet but I plan to soon. Failure to come fully up on advance may account for not coming up on RPM and the plugs being black when I took them out. The carbs are set correctly and sychronized.
Your thoughts on this will be greatly appreciated.