Volvo Penta 5.0 Gi PEFS problem- stumped!

[406Maverick]

Hello all,

Long time lurker around iboats but the past few days have me at the point that I need some help!
1st off I have an appointment a week from tomorrow at a well known shop that is familiar with my boat from the previous owner. But if I can solve it before then it would save me some $$ and I won't have to make the 2 hour drive to the dealer. Anyhoo, here it goes-

Specs of my boat-
2001 Regal lsr2100
VP 5.0 gi pefs sx-m outdrive

I just bought the boat last November- didn't get to do a water trial because it's wintertime up here. It started and ran well on muffs.

Fast forward to the last few weeks. I spent most of the winter fixing up cosmetic issues, but now am getting it ready for summer.

I replaced- distributor cap,rotor, and wires. I replaced the thermostat with a factory 160. I sent out the factory injectors and had them cleaned and flow matched. They checked out. I also disassembled and cleaned up the fuel pump system- ie removed the paint and replaced all o rings etc following the instructions by man cave mechanic on YouTube. I double checked the output and the high pressure stays dead on at 30 and the low pressure at 8-10.

So here's the issue. The engine takes about 8-10 seconds of cranking before fuel even starts flowing from the injectors and it will start. (Sometimes takes multiple cranks before it will start)

I noticed the previous owner had the throttle position sensor unplugged. So I plugged it back in. It now idles smoother, but if I blip the throttle it dies. If I rev it up slowly it revs up fine, but any sudden throttle input it cuts the fuel off. You can see the fuel immediately stop flowing from the injectors (I have the flame arrestor off while testing so I can see the injector flow) If I unplug the throttle position sensor, it idles roughly but will rev up normally and not die when I blip the throttle.

I replaced the iac valve (and have another coming just in case)

I replaced the map sensor- no change

I have tried 3 throttle position sensors

It still starts hard and will not let me blip the throttle without cutting off. I definitely appears that the ecm cuts fuel.

Good oil pressure and good temps..

Any ideas??

 

[406Maverick]

 

[406Maverick]

Also I found this plug/wire on the starboard side of the engine- does it need plugged in or not?

 

[406Maverick]

I was able to make it to the original dealer today, and they ran the codes and this is what they came up with-

14 coolant sensor voltage high
22 TPS voltage low
23 Mat voltage high
34 Map voltage low

They believe my ecm may be on the fritz... any thoughts?

 

[alldodge]

Get a digital multimeter and measure takes some measurements.

Battery reading motor OFF
Battery reading motor ON and has been reved just once to 1200 or so rpms

Check for 5V on MAP and MAT

 

[406Maverick]

Get a digital multimeter and measure takes some measurements.

Battery reading motor OFF
Battery reading motor ON and has been reved just once to 1200 or so rpms

Check for 5V on MAP and MAT

So I am taking the measurements for the battery separately from the MAP & MAT sensors correct? And do I check for 5V on those while the engine is running?

 

[alldodge]

Yes on the Bat, I would like to know the state of the Bat prior to starting. A fully charged Bat would be 12.7V but could be 12.5V

The ECM supplies 5V to sensors, and from your errors it starts to look like a bad sensor is drawing the voltage lower then 5V. Can measure the 5V running or not, but would like to see what it is running. The MAT would be the Tan/Yellow wire, and MAP would be Light Green wire

 

[406Maverick]

Yes on the Bat, I would like to know the state of the Bat prior to starting. A fully charged Bat would be 12.7V but could be 12.5V

The ECM supplies 5V to sensors, and from your errors it starts to look like a bad sensor is drawing the voltage lower then 5V. Can measure the 5V running or not, but would like to see what it is running. The MAT would be the Tan/Yellow wire, and MAP would be Light Green wire

Gotcha- I keep the battery plugged in to a maintenance charger, not sure if that would skew the result or not. As soon as I can I will pull er outside and take the readings of the MAP & MAT.. I appreciate the help!

 

[406Maverick]

Well I decided to send my ECM to Bob @ OBD diagnostics.. and its fried.. so now the search is on for a functioning MEFI 3 or I have to bite the bullet and order a new one or switch to a carb setup..

 

[ChrisCraftFan]

I will let you know how it goes for me with John at Boats Unlimited. He actually takes these apart and replaces components on the inside. He has my mefe 3 now but is backlogged for a week. Bob at OBD is great but I think he is on the software/programming side and John evidently can do more physical component repairs. I will keep you updated as to how it goes. trouble is if you find a mefe 3 you will still need it programmed. I do think Bob has them and can probably program it for you. but he doesn't give them away!!

 

[406Maverick]

I will let you know how it goes for me with John at Boats Unlimited. He actually takes these apart and replaces components on the inside. He has my mefe 3 now but is backlogged for a week. Bob at OBD is great but I think he is on the software/programming side and John evidently can do more physical component repairs. I will keep you updated as to how it goes. trouble is if you find a mefe 3 you will still need it programmed. I do think Bob has them and can probably program it for you. but he doesn't give them away!!

That's a great connection- I will have to give John a call! If John could repair it I'm sure Bob could program it.. I can't even find a used Mefi 3 anywhere right now anyway.. thanks for the help!