150 crossflow wot problem

jy118lfd

Chief Petty Officer
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Jun 18, 2004
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497
Had my 78crossflow v6 out today. Wot 4200 rpm but for about 10 min it ran at 5800 wot while bouncing around in ocean. Could this be the stator? It has 6 new coils(replaced them before it was started) and 2 new powerpacks (no spark on any cylinder and had two new packs from previos motor swapped them and it started) It dosent seem to miss but rpm says it is down on power? Thanks for the replies
 

OBJ

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Dec 27, 2002
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Re: 150 crossflow wot problem

Jon...really sounds like crude floating around in the carb bowls. Just a wee small piece getting sucked into the high speed jet will cut rpm.
 

jy118lfd

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Re: 150 crossflow wot problem

The carbs are clean. I cleaned them twice cause when I fixed the recirc valves one needle and seat somehow got dirt in it and stuck open. I then checked all of the carbs (all orfices) they were all clean. I also had this problem with a total different powerhead. I had a 235 and switched to a 150 (changed the midsection and carbs.) The electronics are the same though.
 

OBJ

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Re: 150 crossflow wot problem

When you cleaned the carbs, did you soak them, then blow them out with air? You really gotta do that to be sure they are clean.<br /><br />On the other hand, you could be dropping a cylinder. Have you checked for spark on all cylinders when this happens?
 

tvpear12

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Aug 25, 2004
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Re: 150 crossflow wot problem

maybe your tack is malfunctioning. did you actually here a diference in the rpms? or i should say the pitch of the engine. did it sound like it lost rpms, or just showed up on the gauge?
 

jy118lfd

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Re: 150 crossflow wot problem

Obj I soaked them and used high pressure air to blow through each orfice. I have been an auto tech for 11 years and have rebuilt many carbs. I am going to test again on tues. I will try to run wot and push the primer choke and see if that changes anything. <br /><br />The tach is new and the old one read the same. The more I think about it the motor did sound different when it was at 5800. The pitch seemed different. I need someone to drive for me as I dont have a test tank. <br /><br />OBJ what is the best way to check spark at wot as I really don't want to hang over the stern at 45mph
 

jy118lfd

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Re: 150 crossflow wot problem

by the way the powerhead is and 83 150 with 83 3 circut carbs (primer choke) and the electronics are from my 78 235. Power packs are new, fuel pumps are new, 6 new coils (newer design). All this was not changed cause of the problem.<br />Power packs changed due to no spark on any cylinder.<br />Coils due to potting cracked and water in them.<br />Fuel pumps cause of broken nipples for fuel lines.<br />This was all done prior to starting engine for the first time
 

jy118lfd

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Re: 150 crossflow wot problem

obj I went out today. 39mph gps 4400 rpm 29psi water pressure it never went to 5800 even intermitently. I tried to push the primer but it just bogged the motor. I tapped it or held it numerous times it always bogged the motor. I shut off the motor at full throttle and pulled the plugs they were all tan and dry no difference between all 6. Does this speed sound right for a 19ft center console? Or should it be higher? This would let me know if the tach is right or the motor was the problem?
 

MarkHPCA

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Jun 2, 2004
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Re: 150 crossflow wot problem

Maybe a dumb question but could it be that the set-up is over proped? You mentioned that the RPM went higher when you were in rougher waters, could this have been due to prop slippage (gulping air etc)?
 

jy118lfd

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Re: 150 crossflow wot problem

Prop is 14 1/4 19 the pitch should be right on for a 19' center consloe. Thanks for the idea though. Sometimes we all overlook the obvious! I wish it was that though my problem is a more of a pain in the a :confused: &%
 

Crossflow235

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Sep 18, 2004
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Re: 150 crossflow wot problem

Sounds like a similar problem I had with my crossflow.<br />(1984 235)<br /><br />Have you checked the advance timing.<br />I purchased my boat last year and ran with the motor all summer and hole shot was terrible and motor wouldn't rev up past 5000 rpm at WOT.<br /><br />Motor did have other problems and thought WOT problem was due to tired motor. Rebuilt motor, all new parts this Aug. Also fixed throttle and carb linkage. (Sync and Link) finished break in hours and tried skiing behind it and was very disappointed. I did verify that timer pointer was set at TDC, base timing was at 8 deg. Assumed that the previous owner had advance timing stop correct.<br /><br />Didn't have test wheel so didn't have way to test advance timing.<br /><br />Was given a given a tip on how to check total advance on motor without hanging onto boat at 5000 rpm, or risk it jumping the trailer. Tip from an Evinrude crossflow expert. (BL Marine)<br />(BLmarine .com)<br />Here is the tip and it works great.<br /><br />Warm up motor, after warming up motor shut motor off and disconnect timer base linkage from throttle lever. Leave timer base at idle position and start up motor. Leave motor in Neutral,Pull timer base linkage so that timer base hits timer base advance stop and check timing. (Motor RPM will increase to about 2000 to 2500 rpm).<br /><br />Adjust timing as per motor specs. (28 Deg max on 87 octane and stock heads).<br /><br />Works great!!! Simple yet effective.<br /><br />Discovered that my motor was only at 16 DEG max advance.<br /><br />Now it takes off as expected and my mileage has also improved. No hesitation. Excellent hole shot.<br />Motor will rev as high as limits or higher (Not recommended)<br /><br />Also there is a better plug for the crossflow than the recommended champion plugs. Bosch Plantium WR9FP. they are about 2.00 each and will definately improve idle on this motor. Minor gains on mileage and horsepower as well. They are a hotter plug so make sure your jetting is correct.<br /><br />I am running a 19' Lavey Craft with a Ron Hill stainless 22. Also have a stainless Raker 20. Running at an altitude of 4500 to 5000 ft.<br /><br /><br />The pitch your running should be fine unless your boat is very heavy, Deep Keel ect.<br /><br />P.S. If you are running motor over 5800 RPM increase oil ratio. VRO pump cant keep up above 5800. 50:1 up to 5700, 40:1 5800 to 6000, 30:1 6500 and higher.<br /><br /><br />Good luck SRP71
 

jy118lfd

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Jun 18, 2004
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Re: 150 crossflow wot problem

Thanks srp thats how I checked the timing. It was at 23 I bumped to 28 and no change thats another reason why I think something else is wrong. I have a used stator coming and I will try that just to see if there is a difference. I am also mixing fuel and oil myself 50 to1 so it is that way all the time. Thanks for the post
 

walleyehed

Admiral
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Jun 29, 2003
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6,767
Re: 150 crossflow wot problem

Disagree with the plug recommendations....<br />Champion QL82C or QL77JC4, possibly QL77V for some of the V6's.<br />Engine was designed around these and piston replacement "can" be an issue if not followed.
 

jy118lfd

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Jun 18, 2004
Messages
497
Re: 150 crossflow wot problem

I have QL16's In it Still cannot get it to go above 4200 on the water. I am going to check it on sat with a fluke meter to see if rpm's are correct but two tachs and two different stators and it still reads 4200. I really don't understand this, cause I went from 23 to 28 degrees advance and changed from 21 to 19 pitch no change in rpm. When the prop slips with to much trim it will go higher. I changed the fuel filter and found some water in it. I flushed the tank and put fresh 50 to 1 still no change!! This is really getting to me now :mad: :confused:
 
Joined
Mar 21, 2005
Messages
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Re: 150 crossflow wot problem

Try checking your Primer/Choke. If it's stuck, left open, or something to that effect, you'll have the same issues.<br /><br />The biggest indication is flooding out at WOT. Seems like most of the other bases are covered already, thought I would throw in a personal issue that took me a long time and wasted parts to figure out.
 

Melvin Hatcher

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Sep 16, 2003
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Re: 150 crossflow wot problem

Originally posted by Nauti Norseman:<br /> Try checking your Primer/Choke. If it's stuck, left open, or something to that effect, you'll have the same issues.<br /><br />The biggest indication is flooding out at WOT. Seems like most of the other bases are covered already, thought I would throw in a personal issue that took me a long time and wasted parts to figure out.
Symptoms sounds familiar, to almost identical to my 1985 XP 150.<br /><br />My plugs are always oily wet, the recirc valves and lines are new. But, the lines are always full of fuel and tends to leak at the connectors. <br /><br />Also, the engine will miss around 3400 - 3800 rpms.<br /><br />Now, how do you test the choke/primer?<br /><br />Regards,
 

Dhadley

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Feb 4, 2001
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16,978
Re: 150 crossflow wot problem

A couple of silly questions -- is the tach(s) set on position 6? Is the linkage going all the way open?
 

Melvin Hatcher

Petty Officer 2nd Class
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Sep 16, 2003
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181
Re: 150 crossflow wot problem

Yes sir, to all of the above . . . and on the second new tach.
 
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