F115txrc stalls/bogs just past idle

[Masonmobilemarine]

Motor will idle pretty well, I can tell the udle is just a wee bit off, but most wouldn't notice it.

If you ever so slightly give it throttle, it will bog bad, or just stall.

You can chop the throttle hard and it will rev up. Sometimes if you ease it bit by bit it will fight through the bog and rev up.

Previously diag fuel pressure reg was bad, replaced that, along with going through all the filters, vst, etc. And ran off a portable tank.


Doing same thing. No codes, the parameters look good. Not sure what's going on.


What would be a cause of this? I think it's fuel related, but it seems to check out...maybe a bad or clogged injector?

[rejesterd]

I would remove the spark plugs and see how they look. If they're a little black, blast them with some brake cleaner then see how it performs. If it's the same, then spray some brake cleaner around the intake manifold at idle while you cover the ISC valve intake with your thumb. If the idle jumps/changes, then you have an air leak. If spark is good and you have no air leaks, then drain the vapor separator and see if any gunk or bad-looking fuel comes out. If so, then maybe the injectors are clogged.

If you have YDS, post a report. Even if there's no codes, the data can reveal something that's not right.

[Masonmobilemarine]

I went through the entire fuel system. Opened up the vst and cleaned it out. Surprisingly it looked really clean, and the filter was hardly dirty at all.

When I removed the water fuel separator, there was rust flakes inside of it from never even being changed (owner didn't even know he had it). I also found the rust flakes on the primary filter on the engine. This lead to cleaning out the vst and going through the fuel system.

I had just rigged up a homemade fuel injector cleaner yesterday using a module to fire off the injectors correctly. I noticed that 2 of the injectors sprayed great. And then I noticed 2 injectors would spray good for a few seconds and then change from a "spray" into like a "flow" of fuel after running for a few seconds. At first I thought I just didn't have enough cleaner inside my gadget, and that it was just a design flaw in the first time rigging it up.

I'm starting to think those injectors got clogged up from the rust debris in the system. Just odd that it would run pretty damn well at idle, can rev high if you chop the throttle, but can't seem to gradually, or steadily increase rpm's.


Btw, this boat has a running issue. Can't get it past 3500...sometimes 2500 rpm, sometimes only gives 3000 rpm....either way....loosing power, and can't reach max rpms.


I did do a drop test with the injectors AND the spark plugs. Both sides of each cylinders always checked out with the drop test. I tried to put a spark checker on it, but its a TCI system and I think I read rodbolt saying something about having to have a special spark tester for TCI systems.

I'm not the best on TCI systems, but I know they are pretty simple. Basically a battery, ecm, and a trigger/pulser coil I think.

[panasonic]

Are the injectors clean now, and spraying properly?

Rust in a fuel system is bad, any contamination is, but I have found rust especially good at getting past filters. And sticking to the insides of fuel lines as well.

I just love to see people still using rusty old 5 gallon portable tanks still.

[TownsendsFJR1300]

Plus 1 ^^^

Your description of the two injectors sounds like rust stuck in there, not pressurizing and dribbling out.

That alone would definitly cause major running issues..

[Masonmobilemarine]

No, I don't think they are clean now. I mostly just rigged it up to test fuel flow and check injectors. Looks like it worked because I found these two.

I will say I noticed that the motor did run differently after running them through my set up. So I do think that's another sign of the injectors.

What do most people do? Send them off to he clean/repaired, or just buy new ones?

I've heard about the "mystery filters" on the hpdi...but I've also heard they are just basket filters that every injector has. Anybody ever replace them? Is it even worth the hassle?

[TownsendsFJR1300]

Most send them off for cleaning as new ones are extremely expensive. Professional cleaners will usually give you a report on before and after cleaning (or failure).

Some folks have cleaned their own, as you could tell, some sprayed good, others didn't

[fairdeal]

I've heard about the "mystery filters" on the hpdi...but I've also heard they are just basket filters that every injector has. Anybody ever replace them? Is it even worth the hassle?

Yes, you can buy and replace the basket filters yourself they are cheap and it is a trivial task

but personally, the ~$20 each injector for a "professional" service is worth it;

typically for that you get
- as found test result of flow & spray pattern
- ultrasonic cleaning
- new basket filter
- new rubber seals
- 'after' flow and spray pattern testing

that quantification of how bad they were
and assurance that they are now 'good'
is IMO invaluable in troubleshooting

[Masonmobilemarine]

I'll have to find a place close by.

Appreciate the advice.

[pstephens46]

I'll have to find a place close by.

Appreciate the advice.

Why? Ship them. They weigh nothing.

Flagship marine?

Brucato?

[pstephens46]

.......................

[Masonmobilemarine]

Was hoping to find local to save shipping time.

Sent out to a place in Naples, FL.

Will post results.

[TownsendsFJR1300]

Was hoping to find local to save shipping time.

Sent out to a place in Naples, FL.

Will post results.

Flagship is about an hour north of Naples. I live in between both..

You should be good thou...

[Masonmobilemarine]

Finally got injectors back and installed. Bad weather was a delay, finally going to run the boat on water today to see how it does.

According to my print out, the injectors didn't leak, but all had terrible spray pattern. Most were down to 58 units (I'm assuming CC? didn't say unit) of flow. One was down to around 52 units of flow. They are all now at 64 units of flow.

Got the injectors back, they were a dull orange all the way around, surprised they could even keep pushing fuel. I'm assuming that was all the rust from the water separator.

Once installed, I hooked up to a fresh portable fuel tank. I noticed it still had a decent bog just past idle. The TPS was just barely in spec, sometimes just a hair over the max spec. I adjusted it damn near to the lowest end of the specs. Seemed to run much better. I tried and tried and tried to get it to stall, wouldn't do it. Think there might have been 2 issues with it....top end not getting enough fuel-therefore limiting revs to 3500ish and not getting on plane. And then the tps being just ever so slightly off and causing stalls just past idle.

Will keep you posted today on results.

[Masonmobilemarine]

Final Update:

Took it out today and it ran great. 5800 max RPM with 2 grown men. 33ish top speed. Definitely underpowered motor for the boat. Reved up nice, idled nice, etc. So a new pressure regulator, cleaning out the fuel system, and cleaning the fuel injectors did the trick.