09 90hp Optimax starts/sluggish idle/then dies

[ggmurray191]

Hello Everyone,

New to the BBC Forum! I'm trying to help a friend at work with his 90hp Optimax. They were out on the water and the Optimax quit and wouldn't start they made it back to the ramp and loaded up and brought it home. Here is the Opti-info Model 90ELPTO S/N 1B735756 and the rundown of what we've done so far. Installed a new primer bulb, a new inline fuel filter added before the VST and a new VST fuel filter. With that done we saw a you tube about the grommet on the high-pressure pump in the VST so bought a new one and opened up the VST for inspection and replaced the grommet and put the VST back together. (The pumps were not tested). The primer bulb was pumped up and discovered leaking fuel on bottom of the VST where the sensor is installed. With a new sensor installed and leak stopped, and new grommet installed we thought we'd be good to go! no such luck . This is the point I decided to swing by with my gauges and lend a hand! At this point I had no idea that there was an air compressor on motor or air regulator so all I had was my trusty EFI fuel tester, complete with a good liquid filled gauge. and after a few more you tubes trying to find out which test port was what I discovered air played a major roll in this fuel system. With my gauge hooked up on the fuel test Schrader valve and key on only position we had 44psi fuel pressure. We tried a couple time all with the same results. I then pinched the return line at the VST and had my helper turn the key to on and it pegged my gauge. figured that meant the pumps were ok!

[ggmurray191]

Thinking the pumps were ok and knowing I had to see both pressures at the same time I quit troubleshooting and went to the parts house for another gauge. Did some studying before I went back again. So Fuel regulator spring is set for 10psi and with the 90+ pounds of air should give 100psi fuel pressure right? With that train of thought I hooked up both gauges and we pulled the boat out in the drive and hooked up the water so it could be cranked up. With the key turned to the key on position 44psi fuel pressure. Then with starter fuel pressure dropped to around 35 and the air gauge 30/35 motor did start up and was sluggish and died. I pulled the air filter tube off thinking maybe the filter was stopped up and cranked up again and got a little longer run time but still sluggish and died. I never saw anything close to 108 fuel and 94 air. I did pinch the line going to the air compressor muffler, but it had no effect on the pressure. So I wrapped things up for the day thinking the air compressor is toast but not 100% sure. $$$$ So I started searching for some help and found the BBC forum and read several posts and got plenty of new things to try! Like applying 80 psi to the air schrader valve with the plugs out and listen for leaks possible air injector and checking the air regulator to open at setpoint etc. hope to get back over to the Opti Sunday or Monday maybe if anyone has a tip or too that would be great! Thanks in advance for any help!!

[JOE54]

80/90 difference in psi running should be around 10psi +- on non pxs mtrs , if air pump is toast it will not run , $$$$$$$ yes failure of comp will require extensive rail and inj cleaning

[ggmurray191]

Thank J54 for the reply, Tuesday before I can get back over to look/test further. Planning on applying some regulated air pressure to the air test port on the rail and listen for leaks and maybe pull the plugs if needed. Anyone have any other ideas or tests to do? Let me know.

[ggmurray191]

EuropeanAM if you happen to read this post, I wonder what you would recommend. Should I continue on and apply regulated air to the rail test port to check for leaks and test to see if the air regulator will operate and dump the excess air to verify its operation.

[EuropeanAM]

Check for air pressure while cranking. It should climb rapidly and reach 90+ psi around the time it lights off.

Low air pressure: Check for leaks in the air side, remove head from air compressor and inspect piston, cylinder, AND REEDS/REED PETAL RETAINERS.

Have seen several where the retainer came loose.

[ggmurray191]

Thanks E-AM for the tips!

With that train of thought I hooked up both gauges and we pulled the boat out in the drive and hooked up the water so it could be cranked up. With the key turned to the key on position 44psi fuel pressure. Then with starter fuel pressure dropped to around 35 and the air gauge 30/35 motor did start up and was sluggish and died. I pulled the air filter tube off thinking maybe the filter was stopped up and cranked up again and got a little longer run time but still sluggish and died. I never saw anything close to 108 fuel and 94 air. I did pinch the line going to the air compressor muffler, but it had no effect on the pressure. So I wrapped things up for the day thinking the air compressor is toast but not 100% sure. The above was from my second trip over to test. My liquid filled gauge is suppose to be in today for the air side. Need a good gauge for testing! I hope to get back over to the motor tomorrow after work. I’ll retest again and report in on the results. After the cranking pressure test if I have low pressures should I follow up with regulated pressure on the air side of the rail??

[JOE54]

yes , listen for leaks

[ggmurray191]

J54 heading over after work, I’ll report in tonight with the results.

[ggmurray191]

Guys, would it be safe to take the belt off and put regulated pressure on the air side and see if the motor will run.

[EuropeanAM]

That can be done, care/caution is recommended.

[ggmurray191]

guys I just spent an hour typing the results and lost it into never never land.....Ugh

[ggmurray191]

Here goes again! Made it back for more testing, but due to time we decided to stay in the garage and do what we could. My new liquid filled gauges came in so I decided to start fresh with all new readings. We started with the fuel side first with key on only tests here are the results. Turned key pumps came on and immediately went to 44psi then shut off and bleed down to 12. We tried this a couple time all with the same results. Next up we I pinched the return line to the VST and turned key on and almost pegged 160psi gauge. We feel like the fuel side is performing ok. ( what do you guys think)? Next up we moved to the air side with regulated air from a small portable air compressor set at 80psi. I had a new liquid filled gauge with a control so we could open or close as needed if we had to. So I hooked up to the air side test port and pressurized the air side to 80 psi and we listened for any air leaks I even took the rubber tube off the outlet of the air compressor to see if I could hear anything but there was no sign of a a leak. That felt like a good sign so I put the rubber tube back on and decided move on the checking the air regulator so we increased the pressure a little at the time until we noticed at 90/92 we heard a strange moaning sound which was the air dumping into the line going to the air muffler, we pinched it off just got a second to make sure. There was no pop and air dumping sound from the regulator only the moaning noise. We assumed it was the regulator doing what it was suppose to. Thought we were pretty much done so I closed the valve on the gauge but noticed the pressure was bleeding off slowly so I thought we found the problem! It’s one of the air injectors so we took the plugs out 1 by 1 and I’m sorry to say there was no leak that we could hear coming out of the spark plug hole. So we were glad it wasn’t one of the injectors! But still at a loss on the air side. Could it be the air regulator diaphragm has a tear and that’s why there was no pop sound or was it working normally. We wanted to pull it but I said no that we weren’t suppose to. Is that really the case can it be done carefully/safely. Maybe it’s torn and that’s why it moans and the air bleeds off slowly. Maybe the air bleeding off is normal. Anyway we pretty much wrapped things up after that. Let me know what you guys think about all this, we hope to do more test cranking outside on Friday. We want to get some cranking readings and take the belt off and put some pressure on the air side and see if it will run. Let’s us know what you guys think!

[JOE54]

are you getting fuel in air side of system after engine is started , if air side is not holding psi there is a leak in system

[EuropeanAM]

It's not uncommon for the air pressure to bleed off "slowly", which is one of the reasons we will usually want pressures at 5/10/15 seconds after the key is turned off.

Beyond that point the pressures aren't of much help.

So what is the air pressure when cranking the engine/starting NOW that you have a decent gauge?

[ggmurray191]

Guys, we got a late start yesterday so we didn’t pull it out and hook the water up, we did as much as we could in the garage for yesterdays readings. Friday we will pull it out and put the muffs on it and get the start/cranking pressures. I’ll report ASAP with those reading! Should we pull the belt and put regulated air pressure on the air side and do a crank/start test to see if it runs decent? The other test will be just start/cranking and see what the gauges say. What other test should we do? J54 mentioned do I have fuel on the airside, how can I check for that? Would that indicate a diaphragm problem. E-AM are you satisfied with yesterdays readings? (Air compressor ok) (air regulator diaphragm ok)…and air injectors. Thanks guys for helping

[ggmurray191]

Guys I have some pictures of the gauge readings and a video of testing the air regulator and the sound it made when it started to bleed air to the muffler. I have to compress the pic some so post it but is there a way to post a short video?

[EuropeanAM]

Put it on a video hosting site, and provide a link here.

[ggmurray191]

Thanks E-AM!

[ggmurray191]

I’m still trying to figure out how to do it E-AM, thought I would upload it to YouTube. Working on it! Would like for you guys to hear the sound it make.