2011 Tahoe Mer 4.3 - engine miss firing

[kbryant]

Hi,
I have this 4.3. I been having an issue when this boat starts to run very rough, almost like it's starving for gas and backfires. I shut the engine down and after about 20 minutes it runs great again for a day or 2 and then it does this rough running and back firing. When you give it gas it just backfires and sounds like it needs gas. I have replaced plugs and wires, dist cap. Any ideas before I bring this in for repairs. It is weird because it runs great and then runs like crap.

 

[Scott06]

Hi,
I have this 4.3. I been having an issue when this boat starts to run very rough, almost like it's starving for gas and backfires. I shut the engine down and after about 20 minutes it runs great again for a day or 2 and then it does this rough running and back firing. When you give it gas it just backfires and sounds like it needs gas. I have replaced plugs and wires, dist cap. Any ideas before I bring this in for repairs. It is weird because it runs great and then runs like crap.

I would start with what do the plugs look like and what does contents of fuel filter have in it?

Is this carbed or injected?

When it miss fires check the spark with spark gap tester, if carbed look down carb and pump throttle to see if there is any gas in carb coming out of accelerator pump

 

[kbryant]

I would start with what do the plugs look like and what does contents of fuel filter have in it?

Is this carbed or injected?

When it miss fires check the spark with spark gap tester, if carbed look down carb and pump throttle to see if there is any gas in carb coming out of accelerator pump

Hello - It is injected. Fuel Filter is clear. Plugs look a little dirty.

 

[Scott06]

Hello - It is injected. Fuel Filter is clear. Plugs look a little dirty.

@alldodge may have some ideas but would suspect that measuring fuel pressure is probably a decent next step

 

[kbryant]

@alldodge may have some ideas but would suspect that measuring fuel pressure is probably a decent next step

I have also noticed that it seems to happen when the fuel tank is around 1/2 tank. By measuring the fuel pressure what would that tell me. Sorry kind of new to this inboard motor. I've always had outboards

 

[alldodge]

I have also noticed that it seems to happen when the fuel tank is around 1/2 tank. By measuring the fuel pressure what would that tell me. Sorry kind of new to this inboard motor. I've always had outboards

Without the correct fuel pressure the engine will not run correctly. With very little or no pressure it won't run at all

 

[kbryant]

Without the correct fuel pressure the engine will not run correctly. With very little or no pressure it won't run at all

What would cause the fuel pressure issue? Thank you for taking time to help me here.

 

[Kola16]

What would cause the fuel pressure issue? Thank you for taking time to help me here.

Clogged fuel filters, clogged fuel pickup tube or screen in the tank, clogged gas tank vent, faulty fuel injectors (won't show up with fuel pressure test), fuel pump going bad. Just measure the fuel pressure. The gauge can be rented for free basically at O'Reilly or the like.

 

[Scott06]

to add tot the list above of possible issues bad pressure regulator, stuck anti siphon valve

 

[kbryant]

to add tot the list above of possible issues bad pressure regulator, stuck anti siphon valve

Here is a question: -- So I bought my boat into a tracker dealer for the above issue I have been having. Has anyone heard about this issue that has caused my problems? The only thing they could find was a bad battery cable. Has anyone had that issue before and if so, did it fix the problem. I'm a little nervous taking it out on the water.

 

[nola mike]

to add tot the list above of possible issues bad pressure regulator, stuck anti siphon valve

Also if only when fuel is low there could be a break in the pick up tube

 

[Scott06]

Here is a question: -- So I bought my boat into a tracker dealer for the above issue I have been having. Has anyone heard about this issue that has caused my problems? The only thing they could find was a bad battery cable. Has anyone had that issue before and if so, did it fix the problem. I'm a little nervous taking it out on the water.

If there was a bad connection and ecu doesn’t get the power it likes sure could happen. Take it out for test run but stay close to the launch or where ever you keep it.