Articles
   
       
       
Pics/Video
   
       
       
Shop
Search
 
 
 
 
 
Home   Articles   Pics/Video   Gear   Wake 101   Events   Community   Forums   Classifieds   Contests   Shop   Search
WAKE WORLD HOME
Email Password
Go Back   WakeWorld > Boats, Accessories & Tow Vehicles

Share 
Reply
 
Thread Tools Display Modes
Old    Boarder85 (fouroheight68)      Join Date: May 2006       05-16-2013, 10:38 PM Reply   
I purchased an 02 Centurion knowing it had a "bogging" issue at 3k+ rpms once it was fully warmed up, altough fairly intermittent. Tested the fuel pump out of the water, and a perfect 43 psi. Took it out for a water test today with a fuel pressure gauge hooked to the test port. I ran it for about 30 minutes, back and forth on the water, again a perfect 43 psi. After about 30 mins, it started bogging, and I checked the pressure. When the bogging was about to occur, I noticed a noticble 5 psi tick down in pressure. When it bogged, it dropped all the way to 10 psi. This 100% eliminated any other issues other than the fuel pump.


The mercruiser mag mpi 350 has 2 pumps. One in the fuel cooler (high pressure) and the priming pump (low pressure) at the fuel water seperator. Im guessing the issue is with the high pressure, considering there is no issue at idle or in neutral; only under load and 3k+ rpms. Does anyone know exactly how the 2 fuel pump system works? Am I right here in thinking its the high pressure pump? I have a new one on the way. Has anyone replaced the fuel pump from the genII fuel cool system? I purchased the pump separate from the cooler.
Old    William Burell (williamburell)      Join Date: Sep 2011       05-17-2013, 6:13 AM Reply   
Ok heres the deal. Right before the LP pump by the water seperator is a deutsch plug for the pump. My money says that the plug is crap. For a quick test remove the plug and solder the wires together. I've seen this over and over again. I'm not saying its your issue but I'd bet a dollar on it. When that plug gets hot, jiggles, etc the connection becomes crap. I'd give that a try before you spend $$$ on the pumps especially since they are $$$ and hard to find. Also when you do this do not pressure test it outside of the water. The same reaction WILL NOT happen if the boat is not under load. While you are there check all your other connections to the pumps. Look for any crappy electrical connection. To me though this is screaming bad connection.

If that doesn't work hit me up. I have a few of the lp pumps laying around.

Last edited by williamburell; 05-17-2013 at 6:18 AM.
Old    Boarder85 (fouroheight68)      Join Date: May 2006       05-17-2013, 8:22 AM Reply   
Wouldn't a bad connection cause the problem all the time (under load or not under load)? Also, what leads you to believe it's on the low pressure side? I was thinking the high pressure pump was the culprit since the problem occurs under heavy throttle/load, yet doesnt die completely (i.e. HP pump cutting out, but LP still running so it doesn't die completely)
Old    Boarder85 (fouroheight68)      Join Date: May 2006       05-17-2013, 8:36 AM Reply   
Is this the plug youre referring to?
Old    Boarder85 (fouroheight68)      Join Date: May 2006       05-17-2013, 8:37 AM Reply   
Also, I pulled the anti siphon valve, blew compressed air through it and it was working properly.
Old    Jay T. (wakebrdjay)      Join Date: Apr 2008       05-17-2013, 8:44 AM Reply   
William Burell may be right.My boat did this exact thing.(Black Scorp.)When I changed the impeller last season I disconnected that and forgot to reconnect it.Boat would run normal under~2K rpm try to go above that and would do just what yours is doing.I was like crap now what then it hit me to check that connection.Yes that is the connection you have circled above.
Old    William Burell (williamburell)      Join Date: Sep 2011       05-17-2013, 5:33 PM Reply   
hey sorry for not jumping back on here for this. Wifey had me digging french drains and putting sod in all day.

Quote:
Wouldn't a bad connection cause the problem all the time (under load or not under load)?
Nope. Full consumption is far diff under load and not.

The plug you have circled is the correct one to hardwire. Make sure you solder it though. It reacts terrible to any other connection. I figured out how to bypass that connection at one point before to test it but for the life of me I can't remember how I was shown.

Quote:
William Burell may be right.

Im not just another pretty face. Other questions to be asked are if the gas had stabil put in it over winter, if the fuel filter has been changed, etc.

There are a slew of problems with these engines just fyi that you should read up on. The dizzy caps are garbage due to a manufacturer flaw and the iac's are crap also.

Last edited by williamburell; 05-17-2013 at 5:37 PM.
Old    Boarder85 (fouroheight68)      Join Date: May 2006       05-17-2013, 9:52 PM Reply   
William - I took your advice and checked the connection. It was cherry, not a spec of dirt, fraying, anything. Looks brand new.

I think I figured out the problem -

I traced the wire for the high pressure pump to the starter selenoid it picks up direct power. The wire at the selenoid was so loose it could be spun by hand. I carefully tightened the nut on the post, until *snap* the post snapped on me! It was an aftermarket starter the previous owner installed. Arghh... I pulled the starter and a new one is on it's way. Im almost positive it was the loose connection, which would make sense.

Last edited by fouroheight68; 05-17-2013 at 9:56 PM.
Old    William Burell (williamburell)      Join Date: Sep 2011       05-18-2013, 2:38 PM Reply   
Well good. I would still solder the connection. Its a worthless useless plug. Mine looked perfect too but was the issue. Its not the actual connection between the 2 but the connections inside the plug. The heat makes for expansion etc and can cause nothing but issues.

BTW do not order a cheap starter for that engine! There are numerous starters on the net labeled for that engine........that aren't for that engine. I purchased a cheap one, shredded it in less than a month, got a replacement and did the same. If you are working with a dd get ready for a pain in the a$$. Its not a 20 min change out.
Old    Jay T. (wakebrdjay)      Join Date: Apr 2008       05-19-2013, 7:23 AM Reply   
IAC is in a PITA place to get to,don't you have to remove the plenum to get to it?
Old    Boarder85 (fouroheight68)      Join Date: May 2006       05-20-2013, 12:06 PM Reply   
Quote:
Originally Posted by williamburell View Post
Well good. I would still solder the connection. Its a worthless useless plug. Mine looked perfect too but was the issue. Its not the actual connection between the 2 but the connections inside the plug. The heat makes for expansion etc and can cause nothing but issues.

BTW do not order a cheap starter for that engine! There are numerous starters on the net labeled for that engine........that aren't for that engine. I purchased a cheap one, shredded it in less than a month, got a replacement and did the same. If you are working with a dd get ready for a pain in the a$$. Its not a 20 min change out.
It's a V drive - I was able to pull the starter in about 15 mins (bolts from the bottom). Shouldnt be any harder to get back in. Also have a new fuel pump on it's way, but I'll try the new starter selenoid first. Im guessing it was arcing on the post , weakening the copper, causing it to fail at the connection (where it broke) when torqued.
Old    Justin Rhodehouse (jrhodeho)      Join Date: May 2010       05-24-2013, 9:42 AM Reply   
When you fix this issue can you post what was the excact issue? I have a 1999 Ski Centurion that does the same thing. Can't figure it out. I was in Havasu last weekend and ran the boat hard for three days straight (not pulling wakeboarders or tubers) without an issue. This week after 3-4 runs of wakeboarding same issue as yours. It's happens everytime while pulling under a load. I go get out of the hole and nothing. Boat boggs down with no power. If I leave it idling for about 5 minutes it clears up and runs fine. I do not have a low pressure fuel pump in my boat. I was thinking high pressure fuel pump but should'nt your fuel pressure be the same under a load or not? I thought the computer just calls for more fuel from the injectors? Any help would be great!

Thanks,
Justin
Old    Boarder85 (fouroheight68)      Join Date: May 2006       05-28-2013, 9:07 AM Reply   
Hey Justin. In my case, Im 90% sure it was a bad power connection for the fuel pump. The first step you need to do is determine if it is an ignition (spark) or fuel issue. To do this, hook up a fuel pressure gauge to your motor. If it is fuel injected, there should be a test port (looks like a tire valve) on the manifold somewhere. If your pressure drops when the it bogs, it is definitely a fuel problem. From there, start at the tank and work your way to the pump. Pull the anti-siphon valve, blow compressed air in the lines, check your filter, your fuel water separator, wiring to the pump, etc.

Regarding your question on whether the pump should work regardless of fuel required, not true. The engine and pump have a much larger load (electrical load) on WOT demand versus idle. If the connection is poor, it will heat up and not give the proper impedance for the pump to supply the motor adequately.
Old    Anthonyv911 (tonyv420)      Join Date: Jul 2007       05-28-2013, 3:20 PM Reply   
IAC is easy to change, its right on top of the motor, and I agree, they are crap! I've changed mine twice, trying to get my starting prob fixed. It still wont start, without putting into neutral and gassing it up. Ive had this problem for two years now!

Reply
Share 

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On



All times are GMT -7. The time now is 1:21 PM.

Home   Articles   Pics/Video   Gear   Wake 101   Events   Community   Forums   Classifieds   Contests   Shop   Search
Wake World Home

 

© 2012 eWake, Inc.    
Advertise    |    Contact    |    Terms of Use    |    Privacy Policy    |    Report Abuse    |    Conduct    |    About Us