Hesitation when accelerating

[Leirhiht]

Last Sunday we took the boat out and surfed for about 3 hours and then on my last pull the engine started to hesitate when accelerating. I drained all the bags and headed towards the dock. Once I got close to land I tried to go again giving it some gas it didn't do the hesitation. So I stopped and went again. Still nothing. So I filled a bag up so someone could surf. They got one ride in and on the second pull it started the hesitation again.

Any thoughts?

2008 mobius lsv. 5.7L indmar.

[trayson]

Start with the distributer cap/rotor.
Then the fuel filter
then try the plugs and plug wires (including coil wire).

Sometimes you have to throw some basic "tune up" parts at these engines. If you replace something that wasn't actually causing the problem, at least you're ahead of the game on routine maintenance.

[Leirhiht]

Start with the distributer cap/rotor.
Then the fuel filter
then try the plugs and plug wires (including coil wire).

Sometimes you have to throw some basic "tune up" parts at these engines. If you replace something that wasn't actually causing the problem, at least you're ahead of the game on routine maintenance.

OK I will. I did the the fuel filter yesterday but couldn't test run cause it was raining. I just hope I didn't get gas from a station that had water in the tanks..
I forgot to mention that I put it in neutral and revved it and on the second Rev it died. I restarted it and it sounded like a rought start but smoothed itself out.

[Alerberg]

WTF! I just replied and hit enter and it disappeared! Again! Anyway, I had this problem on a 2004 Moomba outback, I pulled off the rear ski locker panel to locate the fuel filter and found a kink in my fuel hose. I simply cut off 6 inches which removed the kink, and re-attached. Never had the hesitation problem again!

[trayson]

WTF! I just replied and hit enter and it disappeared! Again! Anyway, I had this problem on a 2004 Moomba outback, I pulled off the rear ski locker panel to locate the fuel filter and found a kink in my fuel hose. I simply cut off 6 inches which removed the kink, and re-attached. Never had the hesitation problem again!

Maybe it was trying to censor your stories about kinky Ho's! (Oh, I mean "hose")

[Leirhiht]

Hahaha

I didn't see a kink when I replaced my filter. I got the cap and rotor and plugs from GM. Waiting on wires from indmar. Hopefully it is just a fuel filter that would bexplain a relief. My biggest concern is water in the tank but I don't fill up at a marina.

[Leirhiht]

Does anyone know the torque specs for the spark plugs on the 5.7 assault engine? Should dielectric grease be used?

[Leirhiht]

Ughhh!!! Now my check engine light is on. I did cap and rotor and fuel filter. Went around the lake a little and still had the hesitation at surf speeds and at higher speeds. The tachometer would beat 3000 and drop to 2700, 2800, or even 2500. I stopped the boat and sitting still in the water it would idle at normal rpm range and I notice it drop to 500 and struggle to get back to 1000. The. My check engine light came on. Sucks cause labor day is next week and I'll probably be take it to the dealership instead of getting on the lake.
Any ideas what it could be??

[trayson]

Ughhh!!! Now my check engine light is on. I did cap and rotor and fuel filter. Went around the lake a little and still had the hesitation at surf speeds and at higher speeds. The tachometer would beat 3000 and drop to 2700, 2800, or even 2500. I stopped the boat and sitting still in the water it would idle at normal rpm range and I notice it drop to 500 and struggle to get back to 1000. The. My check engine light came on. Sucks cause labor day is next week and I'll probably be take it to the dealership instead of getting on the lake.
Any ideas what it could be??

MY CEL light was on too. I replaced the corroded cap rotor. I replaced the plugs. it was better, but not fixed. My RPM's would jump around just like you're talking about, with a 3k variance. It was still running bad and unreliable.


Start with the distributer cap/rotor.
Then the fuel filter
then try the plugs and plug wires (including coil wire).


I got mine from Bakes and they shipped it wicked fast. (or hit up ski-dim, as they're probably closer to you) or even better, find the plug wires locally and throw them on!

I used the 5% coupon code.
MmbaCrw5

These are the plug wires that I used with my Indmar 340 CAT engine. I'm not sure if you have the HVS distributor or not, but it might be the same ones.
http://www.bakesonline.com/detail.aspx?ID=843

It hurt a little to cough up over a c-note HOPING it would solve my problem, but when it DID solve my problem, it was WAY cheaper than a dealer visit. I would have probably spent that much just to have them pull the stupid codes with no insight! Plus, you know how quickly things happen at the dealer??? Plan on having your boat down for 1 to 2 weeks while they get around to it if it's anything like up here.

[Leirhiht]

MY CEL light was on too. I replaced the corroded cap rotor. I replaced the plugs. it was better, but not fixed. My RPM's would jump around just like you're talking about, with a 3k variance. It was still running bad and unreliable.



I got mine from Bakes and they shipped it wicked fast. (or hit up ski-dim, as they're probably closer to you) or even better, find the plug wires locally and throw them on!

I used the 5% coupon code.
MmbaCrw5

These are the plug wires that I used with my Indmar 340 CAT engine. I'm not sure if you have the HVS distributor or not, but it might be the same ones.
http://www.bakesonline.com/detail.aspx?ID=843

It hurt a little to cough up over a c-note HOPING it would solve my problem, but when it DID solve my problem, it was WAY cheaper than a dealer visit. I would have probably spent that much just to have them pull the stupid codes with no insight! Plus, you know how quickly things happen at the dealer??? Plan on having your boat down for 1 to 2 weeks while they get around to it if it's anything like up here.

So once you changed plugs and wires your issue went away? What about your CEL? Did that just turn off or did you clear it with a scan tool? I'll definitely do it Saturday. I'm still waiting on the wires..

[trayson]

So once you changed plugs and wires your issue went away? What about your CEL? Did that just turn off or did you clear it with a scan tool? I'll definitely do it Saturday. I'm still waiting on the wires..

So first, I changed the plugs/Cap/distributor. And when the problem persisted (albeit somewhat better), I then moved onto the plug wires. Yes, I was getting a CEL that was staying illuminated most the time. After changing out the wires, YES, the CEL went away and has never come back. The motor ran amazing after the new plug wires. I got my boat up to 42mph at 5500 RPM's and I hadn't seen that kind of speed in a long time. Purrs like a kitten.

The wires I got were easy. Numbered and ready to go. I did have to remove the cap again to get to the coil wire (required me to take off a sensor above the distributor and also take one bolt out of a bracket and pivot it out of the way to get to the coil wire that was kind of below the distributor area, but seriously, it was a quick and easy swap to do the wires.)

[Leirhiht]

So first, I changed the plugs/Cap/distributor. And when the problem persisted (albeit somewhat better), I then moved onto the plug wires. Yes, I was getting a CEL that was staying illuminated most the time. After changing out the wires, YES, the CEL went away and has never come back. The motor ran amazing after the new plug wires. I got my boat up to 42mph at 5500 RPM's and I hadn't seen that kind of speed in a long time. Purrs like a kitten.

The wires I got were easy. Numbered and ready to go. I did have to remove the cap again to get to the coil wire (required me to take off a sensor above the distributor and also take one bolt out of a bracket and pivot it out of the way to get to the coil wire that was kind of below the distributor area, but seriously, it was a quick and easy swap to do the wires.)

Sounds good. Thanks for the replies! this makes me feel a lot better.

[Leirhiht]

So first, I changed the plugs/Cap/distributor. And when the problem persisted (albeit somewhat better), I then moved onto the plug wires. Yes, I was getting a CEL that was staying illuminated most the time. After changing out the wires, YES, the CEL went away and has never come back. The motor ran amazing after the new plug wires. I got my boat up to 42mph at 5500 RPM's and I hadn't seen that kind of speed in a long time. Purrs like a kitten.

The wires I got were easy. Numbered and ready to go. I did have to remove the cap again to get to the coil wire (required me to take off a sensor above the distributor and also take one bolt out of a bracket and pivot it out of the way to get to the coil wire that was kind of below the distributor area, but seriously, it was a quick and easy swap to do the wires.)

OK changed plugs, wires, fuel filter, cap and rotor. Cel went off after I start and stopped engine three times. Seemed to be working fine cruising to the dam at 25 mph. Gave it a little more throttle and then it started again! Thought I had it fixed. What's the next step you think?

[trayson]

OK changed plugs, wires, fuel filter, cap and rotor. Cel went off after I start and stopped engine three times. Seemed to be working fine cruising to the dam at 25 mph. Gave it a little more throttle and then it started again! Thought I had it fixed. What's the next step you think?

wow. i really thought that would do it. Now I'm stumped. :-(

[Leirhiht]

wow. i really thought that would do it. Now I'm stumped. :-(

Me either.I posted that while on the lake. I sat around in idle for about 20-30 mins. Took off again worked fine. Pulled a rider at surf speeds,fine.

[Leirhiht]

wow. i really thought that would do it. Now I'm stumped. :-(

I posted that as I was on the lake..so i stopped and idled for a while, 20 mins or so, and tried again and it worked great. So I weighted it for my girl to ride and it performed with no issues. Monday I had 5 people including me weighted 60% on non surf side and 80% on surf side (guesstimate) with the suck gate. Performed fine again. Took a break with engine off, started back up after 15 mins and took off. Did the hesitation again, took off fine but in the 3k rpm range it had a stutter. Stopped and idled a bit crawled to dam at 7mph and pulled another rider, back to normal. 3 hours later did it again so I idled and it stopped again. Some sort or sensor fail? Bad gas? Cel never came back on..clueless.

Thought I'd give an update..

[smokeysevin]

Check fuel pressure. Our carbed assault 325 had the fuel pump shit the bed and it was starving the engine until it bit the ghost. If the 340 has the same goofy fuel pump setup you may also want to replace the pressure solenoid next to the destributor. Also check for leaks in the exhaust hose.

Sean

[Leirhiht]

Check fuel pressure. Our carbed assault 325 had the fuel pump shit the bed and it was starving the engine until it bit the ghost. If the 340 has the same goofy fuel pump setup you may also want to replace the pressure solenoid next to the destributor. Also check for leaks in the exhaust hose.

Sean


Cool I'll check that this weekend. Been so busy haven't been able to get back out. Mines the 325 EFI so I really hope it's not injector(s). I was trying to locate the regulator and had trouble finding it. Assuming it is an injector, can I just take them out and hook them to a battery and spray carb cleaner through them? It idles fine and it doesn't do the surging at low speeds, 7-8 mph, but does it at surf speeds with or without perfect pass on, and at 20-25 mph. Is the fuel pump the little electrical solenoid looking part, size of a fist, on starboard side near the floor? I'm stressing out about this cause I don't think extended warranty will cover fuel issues and I don't want to take it to the dealership unless I have to.

[smokeysevin]

Cool I'll check that this weekend. Been so busy haven't been able to get back out. Mines the 325 EFI so I really hope it's not injector(s). I was trying to locate the regulator and had trouble finding it. Assuming it is an injector, can I just take them out and hook them to a battery and spray carb cleaner through them? It idles fine and it doesn't do the surging at low speeds, 7-8 mph, but does it at surf speeds with or without perfect pass on, and at 20-25 mph. Is the fuel pump the little electrical solenoid looking part, size of a fist, on starboard side near the floor? I'm stressing out about this cause I don't think extended warranty will cover fuel issues and I don't want to take it to the dealership unless I have to.


Fuel pump is located near the front of the motor on the bottom, opposite the alternator. I would be surprised if an injector went bad unless you got a bad batch of fuel or water got in the tank.

Sean

[Leirhiht]

Fuel pump is located near the front of the motor on the bottom, opposite the alternator. I would be surprised if an injector went bad unless you got a bad batch of fuel or water got in the tank.

Sean

Well turns out I got high and low fuel pressure pump. When I get to test it this weekend how will I know which one is failing? Boat seems to do the same thing in 3k rpm and higher. And it idles fine..

[smokeysevin]

Well turns out I got high and low fuel pressure pump. When I get to test it this weekend how will I know which one is failing? Boat seems to do the same thing in 3k rpm and higher. And it idles fine..

Making an assumption here since I don't know on your boat. I am guessing the low pressure pump is in the tank and the high pressure feeds the fuel rail/fuel inlet to the injectors. You want to check that the low pressure feeds from the tank is high volume, the one feeding the injectors is high pressure. To check the low volume one, take a gas can and run the pump straight into that, it should feed quite a bit with the end open.

I would check the fuel pressure on the high pressure feed line, it should be somewhere halfway close to 43psi (that's kind of standard but I am not sure what the TBI needs)

Sean

[trayson]

Making an assumption here since I don't know on your boat. I am guessing the low pressure pump is in the tank and the high pressure feeds the fuel rail/fuel inlet to the injectors. You want to check that the low pressure feeds from the tank is high volume, the one feeding the injectors is high pressure. To check the low volume one, take a gas can and run the pump straight into that, it should feed quite a bit with the end open.

I would check the fuel pressure on the high pressure feed line, it should be somewhere halfway close to 43psi (that's kind of standard but I am not sure what the TBI needs)

Sean

I don't know where the 2 fuel pumps are on the 325 assault, but on my 340 CAT engine, they're both right next to each other at the front of the engine (towards bow) on the starboard side, just under the remote oil filter.

[aerolland]

[emoji115] [emoji115] [emoji115] Trayson is correct, it's the same as in his motor.

Sent from my Nexus 6 using Tapatalk

[Leirhiht]

Well finally got to test the fuel pump, been a month or more dealing with the wrong parts and bad weather but it seems to be working fine now. I'm still skeptical becuase after I did the plugs,wires,cap and rotor it worked fine then started again. Hope shes fixed and the last run wasnt a fluke because of weather changes or because the boats been in storage a while.
I'll keep ya posted, if anyone's still reading this post....
Lol

[Leirhiht]

Well it did it again. Does anybody have any other ideas? I'm trying to find a dealer close by that will use my extended warranty. One dealer told me I need to go where I bought the boat...3.5 hours south! :mad:

[Whitey]

Well it did it again. Does anybody have any other ideas? I'm trying to find a dealer close by that will use my extended warranty. One dealer told me I need to go where I bought the boat...3.5 hours south! :mad:

Try some HEET it could just be some water in your fuel.

[trayson]

if you're possibly thinking it's fuel related, then the best thing to do would be to get some good fresh ethanol free gas and bypass your gas tank and have the fuel pump sucking fuel right out of a gas can. However, your problem seems to happen after some run time, right?

I wish I had more ideas for you. But I'm as stumped as you.