| Author |
Message |
    
Dale Thompson
New member
Username: rowdyroady
Post Number: 1
Registered: 06-2009
| | Posted on Monday, June 29, 2009 - 06:37 pm: | 
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I have a 2001 Chris Craft with twin 5.7 GSi's with 270 hours on each. I just bought the boat, and it ran fine when I bought it (of course) but shortly thereafter it started getting sluggish at plane, losing power before finally just refusing to go over 2200 RPM or so. It runs rough and absolutely wants to shake itself off of its engine mounts anytime I try to throttle up. I changed the plugs, distributor cap, rotor and fuel filters. One fuel filter had some watery rust in it which I assumed was my problem at least for one engine...the other filter did not have any water in it. However, both engines display the same symptoms. The fuel pumps are fine, both high and low pressure are good. I have since added some Sea Foam to the one gas tank, and checked the gas filter several times...I seem to have gotten the moisture out.
I am at a complete loss on what to do next...this is extremely frustrating. Please help! |
El Pescador
Senior Member
Username: el_pescador
Post Number: 4567
Registered: 02-2006
| | Posted on Monday, June 29, 2009 - 06:45 pm: |
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See if this helps.
http://www.marineengine.com/discus/messages/12487/84986.shtml
Also, check if the anti-syphon valve is stuck in the fuel tank.
Also, how old is the gas? |
Dale Thompson
New member
Username: rowdyroady
Post Number: 2
Registered: 06-2009
| | Posted on Monday, June 29, 2009 - 11:01 pm: |
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No EPM codes. I thought the boat was entering Safe Mode as well...my first thought...but no ECM or whatever you call it codes stored whatsoever.
New gas...the boat started exhibiting these symptoms a few weeks after I got it...prior to a refill. New gas, full tanks, but the symptoms started before the gas fill. |
Dale Thompson
New member
Username: rowdyroady
Post Number: 3
Registered: 06-2009
| | Posted on Monday, June 29, 2009 - 11:03 pm: |
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Two separate tanks...80 gal each for each engine. Strange both engines are exhibiting the same symtpms. |
LI Monterey
Member
Username: monterey262
Post Number: 43
Registered: 08-2006
| | Posted on Tuesday, June 30, 2009 - 09:07 am: |
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Time for a compression test. |
El Pescador
Senior Member
Username: el_pescador
Post Number: 4572
Registered: 02-2006
| | Posted on Tuesday, June 30, 2009 - 10:09 am: |
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A compression test won't hurt, but it seems odd to me that both engines would have at the same time valve or piston ring problems with just 270 running hours.
Dale, perhaps the seller knows something you don't? Perhaps the boat was stored for a long time and the gas has gummed-up the fuel system. Your engine seems to be TBI, in which case around each injector (part 7) there is a fine fuel filter (part 8). You should have 2 of those filters on each engine. Have you checked them?
http://www.volvopentastore.com/THROTTLE_BODY_INJECTION_SERVICE_KITS/dm/cart_id.9 63744532--session_id.643204790--store_id.366--view_id.312800 |
LI Monterey
Member
Username: monterey262
Post Number: 45
Registered: 08-2006
| | Posted on Tuesday, June 30, 2009 - 03:16 pm: |
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Totally agree with El that this would be weird to impact both engines with low hours. Certainly does sound likely to be a fuel related issue. But burned valves would also exhibit similar symptoms. Are the engines back firing? What did the old plugs look like? |
Dale Thompson
Member
Username: rowdyroady
Post Number: 4
Registered: 06-2009
| | Posted on Tuesday, June 30, 2009 - 04:04 pm: |
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ALl sixteen plugs were dry...but very sooty and black. Oh, and it was the original plugs...never been changed. No backfiring. I am going to likely turn the local Penta authorized dealer loose on this problem as much as I hate to do that. I am at wits end, and running out of ideas. Also, don't have any experience with TBI... |
LI Monterey
Member
Username: monterey262
Post Number: 47
Registered: 08-2006
| | Posted on Wednesday, July 01, 2009 - 09:14 am: |
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Looks like it was running rich and that would point to a TBI/ECM related problem in my opinion. Did you check the throttle valve operation and the throttle position sensor (TP)? Maybe it is sticking and restricting the air flow? I believe TBI has 2 injectors and their tips are located above the throttle valve. The injector timing is controlled by the ECM and various sensors that monitor engine conditions and places the ECM into different fuel modes. I wonder if your TP sensor is bad and keeping the ECM in the acceleration mode. That would provide extra fuel by increasing the injector pulse rate and definitely load the cylinders with fuel. The ECM code would be code 21 or 22. This can be checked with a DVOM. |
LI Monterey
Member
Username: monterey262
Post Number: 49
Registered: 08-2006
| | Posted on Wednesday, July 01, 2009 - 09:27 am: |
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Dale,
As a disciple of EL, I am a big believer in the SELOC manuals. Everything you need to troubleshoot the problems is there. |
Dale Thompson
Member
Username: rowdyroady
Post Number: 5
Registered: 06-2009
| | Posted on Wednesday, July 01, 2009 - 12:54 pm: |
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Li,
THanks for the input...I just purchased the SELOC manual. Should have in a week. In the meantime I will check the TP sensor although I had my dealer check the ECM...no codes recorded. |
LI Monterey
Member
Username: monterey262
Post Number: 51
Registered: 08-2006
| | Posted on Wednesday, July 01, 2009 - 02:44 pm: |
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Dale,
I'm not 100% sure the TP will throw a code; SELOC isn't clear on that and I have seen cases where there wasn't a firm code and the TP was bad. You can use a DVOM to check, I will summarize directions in following posts. |
LI Monterey
Member
Username: monterey262
Post Number: 52
Registered: 08-2006
| | Posted on Wednesday, July 01, 2009 - 02:53 pm: |
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TP will send a signal voltage to ECM- 0.7v at idle to 4.0+v at wide open throttle. Beg, borrow or steal a code reader and connect it. With ignition off disconnect TP sensor, start engine and allow to idle for 2 minutes. Turn off ignition and retrieve any stored codes. If code 22 locate and repair any bad connections. If no codes replace the TP sensor. Next step to follow. |
LI Monterey
Member
Username: monterey262
Post Number: 53
Registered: 08-2006
| | Posted on Wednesday, July 01, 2009 - 02:58 pm: |
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With ignition off disconnect TP sensor harness, turn on ignition but do not start engine. connect DVOM between A & B harness terminals. If reading over 4v you have a short to voltage in the circuit between J2-19 and the harness connector C. If everything looks okay then it is in the ECM and it has to be replaced. If the reading is under 4v you have an open ground between J2-18 and the harness connector B. If this checks out okay and the ECM connections are okay, replace the ECM. |
LI Monterey
Member
Username: monterey262
Post Number: 54
Registered: 08-2006
| | Posted on Wednesday, July 01, 2009 - 03:02 pm: |
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In my experience 99% of the time the TP sensor goes bad just like automotive applications. The throttle body gets gummed up, the shaft starts to bind and the TP gets thrown out of whack. All it is is a potentiometer that provides a variable signal to the ECM with the opening and closing of the throttle. Check it and clean as needed and also check the harness connectors going into the ECM. It is probably something simple. |
Dale Thompson
Member
Username: rowdyroady
Post Number: 6
Registered: 06-2009
| | Posted on Wednesday, July 01, 2009 - 05:53 pm: |
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Seems like this is the right path....great info. I will update as soon as I am able. |
