2000 Johnson 175 fuel issues

delphimark

Cadet
Joined
Aug 2, 2008
Messages
12
There is a lot of history here, but I will try to be as brief as possible. Since the middle of last summer, my engine would start, idle, and run perfectly up to about 4800 RPM. At that point, it would act as though it was starving for fuel. It wouldn't die, it would simply bog down, and not gain any more speed or RPM. (In the past, the boat would run about 62 mph, but was only getting about 50 mph out of it). So, in February, I took it to a local shop to have it diagnosed and repaired. I assumed it was a bad VRO, because I had been reading these forums for a while, and it is 17 years old. They diagnosed it as a bad VRO, ordered one, and replaced it. It didn't fix the problem. They then tell me I have a power pack issue. They put a new one on it, call me, and tell me it's fixed! I pick it up, and take it to the lake, and I have the exact same issue. I take it back to the shop, and they proceed to keep the thing for 3 months! The problem when I pick it up is, it now won't run AT ALL! It's very difficult to start, it won't idle. That was two weeks ago. So, I take it to a different shop. This mechanic sees several things the previous shop "broke" while working on my engine. He fixes those, gets it to start, and it seems to be like it was before I ever took it in originally. But, here's the issue now...after about a minute of idling, it runs out of fuel! The bubble is soft and the engine is starved for gas, and dies. I have new carbs, new VRO, new gas lines, new bubble, new coils, new power pack. The mechanic can't seem to track down why it's running out of fuel. Any thoughts would be greatly appreciated.
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
Have you tried squeezing the bulb to keep it running, this would have been the correct test to diagnose the "failing VRO" also, it would have told you immediately if that was the issue.

​You can also use a piece of clear fuel line and watch for bubbles in the fuel, this may help locate an air leak.

​Sounds like lots of replacing parts and not much testing systems by the prior shop.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
2 cycle, carb motor? If so, it sounds like the main strainer is clogged, the water separator is clogged or the antisiphon valve is clogged. It could also be that the vapor pump is defective or the vapor separator chamber is leaking air.
 

delphimark

Cadet
Joined
Aug 2, 2008
Messages
12
Squeezing the bulb will keep it running. But, bypassing the VRO and temporarily using an electric fuel pump caused the same condition. All fuel lines have been replaced, but, there was an attempt to run the engine from a different tank with different lines, with the same results.

I didn't mention that the vacuum pressure switch has also been replaced.

The water separator has been checked, but I'm not sure if anti-siphon valve or the vapor pump have been checked. I'll ask my mechanic today and post his answer.

Thanks guys for your input. It's been terribly frustrating...
 

delphimark

Cadet
Joined
Aug 2, 2008
Messages
12
Chris1956 seems to have been correct! After almost 6 months, the problem has been solved! After replacing the VRO, the coils, the power pack, the carbs, all fuel lines and bulb, plus too many other things to list, it turns out it was the vapor separator. I think my mechanic called it the VST.
I had the opportunity to run it yesterday and was very pleased! It actually ran better than it has in about 5 years!

It wasn't easy to track down! The way he found it was to disconnect the fuel rail to visually check how much fuel was pumping through the pump. With the bulb tight, it pumped fine, but after a few seconds, it got weaker and weaker. He bypassed the VRO and VST, and it pumped perfectly. Knowing the VRO was new (and good), it isolated it to the VST. Replaced it, and all is good!

That part is less than $200. But it took $2000+, and almost 6 months to find it! I hope this helps someone in the future!
 
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