2300V Stalling At Idle

[jjolley55]

Hey Guys,

I bought this boat earlier in the year, and finally got it in the water a couple weeks ago. It's a 2000 2300V with the mercruiser 350 MPI. I'm having an issue with it stalling at idle once it warms up. If I bring the RPM up it seems to run okay. Here's a link to a video showing what it's doing. https://photos.app.goo.gl/71xfm6HRmKu9dBGn9

Here's what I've done so far.

I replaced the IAC valve and that didn't change anything.

The fuel pressure gauge wasn't working, so I replaced that. When I did, the fuel pressure seems to be low from what I've read. Runs about 20psi without the boat running and drops down to around 5psi with it running.

I replaced the fuel pump. Fuel pressure still acts the same.

I replaced the fuel filter. No change.

I checked for vacuum leaks, the best I could. Took a propane torch and went around the intake manifold while running. Didn't notice any changes in idle. I also tried the poor mans smoke test by putting a cigar in a transfer pump. I couldn't see any leaks.

So, what am I missing. Maybe fuel pressure regulator, or whatever temperature sensor controls the IAC? I'm considering buying the Rhinda diagnostic software, but it's pricey.

Thanks for any advice.

[chpthril]

The fuel pressure gauge wasn't working, so I replaced that

Fuel pressure gauge? or oil pressure?

Hows the engine run under load?

[boatwakes]

Did you replace the high pressure fuel pump, the pain in the *** pump located on the engine port side motor mount (because the engine is backwards on a v-drive it will be located on the starboard side of the boat)? That engine has a booster pump located on the fuel filter but its low pressure. The high pressure pump also has the fuel pressure regulator on it and SUCKS to replace the whole unit. Thats the high pressure fuel pump.

[jjolley55]

I replaced the fuel pressure gauge that is on the end of the fuel rail. Not sure if that was factory, or if someone added it. The engine seems to run okay under load. Got it up to where is started bouncing pretty good (Trim tab isn't working either). It seemed like the power would go up and down a bit without me moving the throttle, but that may just be my imagination.

I did replace the high pressure pump. It was a bit of a pain, but the fuel pressure regulator looks like even more of a pain. I haven't looked at the booster pump yet. I will check that in a little while.

Thanks guys!

[boatwakes]

The booster pump will cause the engine to oscillate above 3000rpm or so. It'll swing down to 2500 then back up to 3000 then back down. The fuel pressure gauge on the rail is aftermarket. Years ago I posted a how-to on installing those to help diagnose fuel system problems. If it is indeed reading that low, the regulator may be junk. There's a brass fitting sistered to the regulator, plan on replacing that as well because the threaded nipple on the fitting usually breaks off into the old regulator. Get your serial number and go to perfprotech.com for the parts diagram for that fuel system.

The computer regulates the pulse width of the injectors and above 140 degrees temperature, the engine is considered warm and the injectors fire at half the pulse width. If the fuel pressure is that low, not enough fuel is making it into the engine. If its that low and you're able to run it, you run the risk of blowing the top of a piston off from detonation stemming from a lean fuel condition. Get the fuel pressure sorted first using a known good gauge and we'll go from there.

[Powday]

I had a similar issue at the beginning of the season and solved by replacing the low pressure fuel pump. Went ahead and replaced the fuel filter and water separator while I was at it. Now I’m crossing my fingers I don’t have to replace the darn high pressure one anytime soon, hehe.

http://www.tigeowners.com/forum/show...ht=#post806138

[jjolley55]

I finally had a chance to go work on the boat for a bit today. I noticed that the tube coming from the valve cover up to the spark arrestor had a lot of air moving through it. I plugged that and it solved my stalling at idle issue. It just had a through port in there instead of a PCV valve. Once I put a PCV valve in, that seemed to fix that.

However, I haven't solved the low fuel pressure issue. I took the supply line off the tank and put it in a 5 gallon can to make sure the pickup wasn't clogged. Fuel pressure stayed the same. I tried to clamp the return line to the fuel filter. Fuel pressure stayed the same. Not sure I had it fully blocked. I didn't what to clamp down on it too hard. I looked for the booster pump, but I didn't see one anywhere. I attached a picture of the fuel filter assembly. Am I missing it somewhere?

20190915_153841.jpg

I took it for a quick lake test after I changed the PCV. It runs okay at low RPMs, but does pulse when it gets up over 3,000 RPMs. Guessing that's the fuel pressure issue?

Thoughts?

Thanks,
Jeff

[boatwakes]

There should also be a vacuum hose from just below the throttle body connected to the high pressure fuel pump. Sometimes that gets dislodged or the hose cracks and will cause similar issues. You do not have a booster pump on that engine, just the high pressure pump. What does the fuel pressure do when the engine RPM oscillates?

[AJMichael]

Any update on the outcome? I brought my 02 V21 out for the first time last weekend and at idle the boat would stall out after running for a few.