1985 Johnson GT 150 VRO pump

Hello. I have a 1985 Johnson GT150. Model: J150STLCOH. The oil pump side of the VRO was disconnected before I bought the boat 6 years ago from a family member and oil has been premixed. The motor has intermittently cut out at high speed (over 4,000 rpm) since i have owned it. Last season it started to do it consistently and has been really hard to start first thing in the morning.
In the last couple of years, I have replaced the plugs, coil packs, had carbs rebuilt, replaced all fuel hoses and primer bulb, changed filter yearly, checked pickup tube screens, and checked compression (all 90-95). The primer bulb will not get hard when I pump it up. I would like to look into replacing the VRO pump and still premix. I have seen a dual pump conversion that is much cheaper. Should I go with that or get the more expensive VRO (non oiling) pump? Thanks in advance for advice!!

Are you pushing the key in while cranking it over om cold start?----------Duel pumps were used on the 83 models before VRO.----Bulb MUST go firm and look for that issue.------That is not related to the fuel pump either.

Yes I am pushing in on the key. It used to start right away first thing in the morning. I have not tried pumping it up since I replaced all of the lines. I didn't want the fuel to sit in there til spring

If the fuel ball is not getting hard, do not run the engine until you check this. Look for the pulse limiter on the lower port side of the crank case. Pull the large line off of it, this line goes from the valve on the crank case to the VRO pump. Once the line is removed, pump the fuel ball and see if fuel comes out of the line.

If fuel is present, replace the VRO. Running the engine with the VRO leaking fuel into this line will destroy your power head..

If fuel is present, it will explain a lot of your starting issues.

I am going to replace the pump. Should I mess with the two pump conversion or buy the VRO pump and still premix?

Get the VRO and hook up the oil tank and let it do its job.


You will want to check that pulse limiter anyway, just to know.

Docksidemarineservices said:

Get the VRO and hook up the oil tank and let it do its job.


You will want to check that pulse limiter anyway, just to know.

Click to expand...

Ditto....The VRO is a very reliable and simple oiling system. The VRO got a bad rap because must Techs and owners did not understand how it worked. Most power head problems are caused by dirty carbs and not faulty VRO's

Now is the time...mr racer....to ask him to check his compression.

He doesn't describe the actual shutdown conditions....but it could possibly be a lean condition causing the engine to seize. Always happens at WOT.....happened to me anyway. First engine I ever blew!!!!

Get compression numbers on all six, post numbers, not "compression is good".

No need to check compression at all.----Many new parts and work have been thrown at it.----The next item is the fuel pump , a big $$ item------------If you can solve it with money , you do not have any problems.

The OP said the the compression was 90-95 psi across the board no need to check again. He also describes a high speed miss getting worse. Start by doing the tests on the stator and timer base go to CDI Electronics and find the testing procedure for your motor may need to buy a dva adaptor.

Geee....I keep missing this stuff.....why am I not reading the full details?
Something's wrong....

I coulda sworn he didn't post compression numbers.

flyingscott said:

The OP said the the compression was 90-95 psi across the board no need to check again. He also describes a high speed miss getting worse. Start by doing the tests on the stator and timer base go to CDI Electronics and find the testing procedure for your motor may need to buy a dva adaptor.

Click to expand...

If the VRO pump is leaking his premixed fuel into the crank case through the pulse limiter it will run like a bag of s... and get worse at the pump leaks more.

Didn't say that couldn't be it but he had the high speed miss first. My opinion is different because I would not expect a bad fuel pump leaking into the cyl through the pulse line to provide enough fuel to run the motor above 4000 RPM. I also think the ball not getting hard is more of a carb problem. The high speed power drop off is indicative of a stator JMO.

Sorry it took me a while to get back. I also replaced the stator and regulator a while back. I purchased the fuel pump but have not got it yet. Going to takle that this weekend.