2000 gi pefs 5.0

[GMC 72]

First, Wow. I may find my answer in all the responses on this forum. I just started diving in tonight.

I have a 5.0 GI PEFS while I was on shore my wife driving I could hear a faint pop from the exhaust. I dove in thinking I needed to change plugs and wires all the normal reasons for a pop from the exhaust.

The inside of my spark arrestor was black. Cleaned that. Found a cracked spark plug. Great easy fix. That wasn't it.

Still pops through the exhaust at 2800 RPMS. It is a TBI.

Did compression check 175 cold each cylinder. Happens cold or hot.

Fuel pressure is steady at 45 and 20. I see no issues there.

Here is what bugs me. I checked my Map Sensor. I disconnected the electrical line and the motor ran like a top through 4800 RPMS. Died right after I dropped it down. Thought great I found it. Replaced the MAP sensor.

NO JOY!!! I can make a 1994 Chevy Truck with TBI run like a top. What am I missing?

 

[alldodge]

Howdy
Compression is a bit high or the gauge is not accurate, should be closer to 150

Might have a broken valve spring or worn valve guide. If any of the plugs where black with build up, the maybe the guide.

Did you have any of the plugs wet?

 

[GMC 72]

Yes the plugs did have gas on them. The plugs were clean. Not black or anything abnormal.

 

[GMC 72]

I don't see anything wrong with these. This is even the one that had a cracked Insulator.

 

[alldodge]

Yes the plugs did have gas on them. The plugs were clean. Not black or anything abnormal.

Plugs should never have wet gas on them, so injectors are leaking or the gas was water

The insulator being white it might be the start of steam cleaning

 

[GMC 72]

I sent the injectors out to be cleaned. I thought that might be it. All this started after I put in a new tank of gas. I am going to try an alternate fuel source this weekend. Thank you for the thoughts. I appreciate it!

How do you guys empty the gas tank?

 

[alldodge]

All this started after I put in a new tank of gas.

Take the filter off and pour the contents into a clear container. Let it sit and see if there is anything but clear gas

How do you guys empty the gas tank?

Very carefully :facepalm: sorry had to do it

Remove the antisiphon valve off the fuel tank pickup, and replace with a straight barbed fitting from the hardware store. Connect a fuel line to the tank pickup and run it out the drain hole in the stern. Get it to siphon out

Before doing that, if you find nothing in the filter. Use a 5 gallon gas can and put the fuel line in it and run the boat to see if it does it

 

[GMC 72]

So I got the Boat out on the water today. The back fires are for the most part gone. I had one or two today. Mostly as I brought the throttle back from 3500 or above.

The big issue today was surging. Hard to explain but as I pushed the throttle forward the RPMS would jump to 2000 bog back to 1200 then settle in at 2000. I would push it to 4000 it would bog back to 3200 then settle in at 4000.

The most I could run is at 4000 RPM at Wide Open Throttle.

Going to take it back out and see what the HVP and LVP are reading on the fuel Pressure Monday.

I replaced my Fuel Pressure Regulator Diaphragm. It came with a new spring that is significantly different then the one it had. It was smaller and Shorter. Do I put my original spring back in it. I am also trying to run most of the fuel out of it before trying to siphon the tank.