I think I've worked out the majority of my fuel issues. About a month ago the starboard motor started throwing a "check engine" light at the helm, but I didn't think much of it. I was running the motor for approximately 10 hours, then changing the fuel filter. It would run better with fresh filters, and slowly get worse as the filters clogged. I got to the point where I could tell that the filters needed replacing. I was satisfied with the progress and could use the boat, but was still troubled with the check engine light, that never existed with fresh filters, or even clogged filters in the past.
With partially clogged filters the starboard motor would hesitate under acceleration, but always accelerated fine and give me full RPM with fresh filters. That's no longer the case. The motor now breaks up after around 2500 rpm or so, every time, fresh filters or not, still has a check engine code. Fuel pressure is good, fuel spray pattern out of the injectors looks good. I'm guessing the issue is a bad MAP sensor. What's a good way to diagnose the issue without a vacuum pump?
I was told that the motor may run better, accelerate fine, and run a little rich if I disconnect the MAP sensor. If that is true, I suppose that would be one way to diagnose the issue. Also, can the MAP sensor be cleaned? I will check the vacuum line for leaks, kinks and clogs tomorrow morning.
454 XL Possible MAP sensor issue?
- 390Express
- Captain

- Posts: 238
- Joined: April 6th, 2018, 2:15 pm
- Vessel Info: 1996 390 Trojan Express
- Location: Michigan
- Has thanked: 141 times
- Been thanked: 15 times
- mjk1040
- Admiral

- Posts: 1531
- Joined: July 30th, 2015, 8:15 am
- Vessel Info: 1998 355 AC/MY "Deja Vu"
- Location: Savannah, NY
- Has thanked: 9 times
- Been thanked: 248 times
Re: 454 XL Possible MAP sensor issue?
If not a big hassle, swap out the port engine MAP for the starboard engine. May be a code reader is needed?
Mike
I'd Rather Be Boating!
1989 Sea Ray Seville
1986 Carver Mariner 32'
1990's Thompson 22' Cuddy Cabin
1990's 4Winns 245 Vista Cruiser
1980's Thompson 19' Open Bow
I'd Rather Be Boating!
1989 Sea Ray Seville
1986 Carver Mariner 32'
1990's Thompson 22' Cuddy Cabin
1990's 4Winns 245 Vista Cruiser
1980's Thompson 19' Open Bow
- Bentone23
- Deck Hand

- Posts: 57
- Joined: April 10th, 2018, 10:58 pm
- Vessel Info: 1996 Carver 355 Aft Cabin
454 xli TBI Crusaders - Location: San Francisco Bay
- Has thanked: 57 times
- Been thanked: 5 times
Re: 454 XL Possible MAP sensor issue?
What code reader can I buy for my 1996 Carver 355 Crusader 454xl TBI engines? Where is the ALDL connector?
Bruce Bennett
Bentone23@sbcglobal.net
1996 355 Aft Cabin
Central California
Boating on the Delta and SF Bay
Bentone23@sbcglobal.net
1996 355 Aft Cabin
Central California
Boating on the Delta and SF Bay
- bud37
- Admiral

- Posts: 5182
- Joined: April 23rd, 2015, 10:22 pm
- Has thanked: 604 times
- Been thanked: 1312 times
Re: 454 XL Possible MAP sensor issue?
Check out Rinda Technologies......
FWIW.....The above is just my opinion.
- 390Express
- Captain

- Posts: 238
- Joined: April 6th, 2018, 2:15 pm
- Vessel Info: 1996 390 Trojan Express
- Location: Michigan
- Has thanked: 141 times
- Been thanked: 15 times
Re: 454 XL Possible MAP sensor issue?
Apparently michiganmotorz.com has a MEFI 1 specific computer for $495, similar to this one:
https://www.michiganmotorz.com/techmate ... -4589.html
You can buy a slightly more expensive code reader than can do everything from MEFI 1 to MEFI 4. I'm considering buying the MEFI burn software, which allows for not only the reading and clearing, but also the re-programming of modules from MEFI 1 to 4.
Do you have any experience with any of the above?