Logo
FULL SITE MENU

2006 BF150 Won't Start unless half throttle

K

klammrish

Member
I have read ever post on this site and have read some great ideas, unfortunately nothing has worked. I bought the motor off ebay and it was advertised as none running with 180 PSI Compression on all four cylinders. I have confirmed it has 190 PSI on all cylinders. The motor has excessive soot on the prop and lower unit, Plugs were sooted over. Changed plugs with new NKG and new air/fuel sensor. It has 48 PSI at the outlet of the high pressure fuel filter. Changed the intake air bypass and inspected the throttle body. I have a honda service manual and resistance checked every sensor that I can. I installed jumper on red plug and no codes are showing up. It will start up about half throttle, but runs very rich. It will die as soon as the throttle is moved towards neutral. No buzzers other than the 2 second beep or engine lights. It will run for ever at 1500 RPM, but acts like it is running on half the cylinders. Gas is new and coming out of a portable tank. As you can see, I have made every effort to try everything, before asking for help. HELP!
 
Are you getting a spark on each plug? It sounds like the fuel is not igniting on one or more cylinders. Hence the soot & high idle. You can check by first running it dry of fuel. Removing the plugs and earthing them against a good earth spot on the motor body, of course with the wire and cap attached. That would be the first step if you have not checked this yet.
 
I will pull the top of the VST this evening and inspect. The float needle valve stuck on the other engine and fuel was coming out the vent. Now that you mention this, I bet I have a faulty check valve on the other motor. The check valve should of stopped the fuel flow.
 
I am getting spark. I pulled all spark plugs and replaced with new NKG and I have a spare motor that I pulled the coils off and swapped with no change. Appreciate the suggestion and will continue troubleshoot. It should be the simple combustion triangle (fuel air ignition) I haven't done anything with the VST, I will pull it tonight a check.
 
Have you checked the idle air control? I dont think your needle on the vst is stuck if you are getting 48 psi at vst, I could be wrong and chawk is pretty good with this stuff, but just my opinion.
 
I didn't move the screw as it was painted and factory set. Should I move a turn or two either way? Is there something else I should be looking for
 
Leave the IAC plugged in but remove it from the engine. Try to start the motor. It will probably start and run at high rpm. If it does, then look toward the IAC.

The IAC may be stuck closed. You can exercise the IAC by using a 9 volt battery directly to its two terminals. If you exercise it a few times, it might start operating. You should be able see the plunger moving.

Or better still. Take the one off of the other engine.

That being said, I hope you weren't referring to the IAC when you said you replaced the intake air bypass.

If so, cancel what I just said.

Mike
 
Good Idea, I had swapped it with one from the other, but decided to try it anyway, went out and pulled the IAC. It still just sputtered and tried to start. Fuel vapors released out the IAC holes after start attempt. so it is getting fuel, but still wont start without advancing the throttle.
 
I did just check it. I pulled it and replaced with one from the other motor. I just tried what Mike said to do and run the motor without the IAC on the intake and it still acted the same. Wont start without advancing the throttle and then it runs rich with soot coming out of lower unit. Thanks for the advice still stumped
 
Did you try starting it with the IAC removed but plugged in?

Have you checked to be sure that the timing marks are in line?

If timing is good.....there may be an ECM issue. If the engines are of similar vintage, swap the ECM's. I guess I am hung up on IAC function...

The other key items to idle are the MAP sensors. Remove the MAP sensors and make sure that their openings or the openings that they are mounted on are clear of debris.

One other important piece of the puzzle is valve clearances. Compression may be good even if valve clearances are off.

Mike
 
I did swap the ECM a couple of days ago. The map sensor I haven't tried. I will inspect this evening after work. The timing and clearance issue, I haven't tried and dread pulling the top cover, but it may be my issue.
 
You do not have to remove the top cover yet. You can check the timing marks just by removing the valve cover. You can see the marks when you remove it and use the them at the same time to check the valve clearances. You will have to remove the plastic silencer ductwork on the top.

Chapter 3 of the manual has a step by step on checking timing marks and valve clearance.

Mike
 
Sorry about lack of response, I have had to work a lot of hours this week. Hope to pull cover this evening. I will read up on procedure on Chapter 3. No codes except throttle position popped up when I swapped ECM. Did the reset of safety switch and all codes cleared. Currently no codes.
 
Ooops, I didn't know there were duplicate threads..perhaps delete the other thread..

I would probably check fuel pressure at the fuel rail. I know there is a screen behind fuel rail where the fuel pressure reg is. Are all your ignition coils working? I'm craps shooting here, eventually you'll find the culprit by elimination.
 
Have you checked the intake manifold by chance? Sounds like it is starving for air and many times I have seen rodent nests in exhaust systems but these have very big manifolds for the intake. Great place for a home.
 
The book says the marks should meet at 3 oclock and 9 oclock. I turned the crank to get the intake sprocket at 3 oclock and the exhaust is at 7 oclock. It look like it is off a few teeth. I turned the crank a couple of revs and it repeats the offset every time.The book give the procedure to pull the top and align all the marks. What would cause the motor to jump timing?
 
Looks like a valve intake issue with timing chain alignment. Verified alignment marks are they are off 30 degrees. Need to know the proper way to repair. Just realign or replace parts

thanks

Kurt
 
If the timing were off your compression would be lousy, and the valves would have collided with the piston and bent leaving no compression.
 
I don't know. It looks like no damage. The marks on the two sprockets for the valve cams never line up and the book shows them lined up with number one cylinder at top. The intake cam is where it's supposed to be according to the manual and the exhaust is about 3 teeth off on the sprocket. I haven't touched it yet. Went to parts store to buy the 50mm crank pulley bolt removal. I have a spare block and head. I may just replace the whole thing.
 
If you have the compression you tell us you have, again, I would strongly investigate before doing anything to the timing. I can't think of any reason for a Honda cam chain to jump gears on an outboard but I guess anything is possible, just not likely.
 
It is possible if the chain guides/tensioner failed.

The only way to reset it correctly is the remove the top cover, check the tensioner etc and once problem parts are replaced, set the timing chain by the colored marks on the chain.

The hardest part in the removal process is removing the crankshaft pulley. If you are in the USA and there is an o'reily's auto parts store nearby, I understand that you can borrow the holding tool to break loose and tighten the crankshaft bolt (which is torqued at 181 ft lb). http://www.oreillyauto.com/site/c/rental-tools-program.oap

Pay close attention to the book for the sealant application amounts and pattern, when you go to put it back on.

Before you go through all of that, double check the marks by using a screwdriver in the top cylinder hole, and rotate the crankshaft manually until the marks on the cams are in alignment. Check to see if the screwdriver has been pushed out to the max at that point. If the top piston is really at top dead center, then your timing is definitely off.

Sometimes just a little movement of the crankshaft pulley can sometimes bring those marks on the cams in line.

I always like to check and double check before taking things apart.

Mike
 
Thanks I will try the screw driver tomorrow. I went to Orileys today and bought the 50mm tool for 23 dollar. Thanks for the detailed response. I haven't taken anything apart other than the valve cover. So all timing is factory and sealant looks original on top cover. If it is off, it must be a tension issue.
 
If that motor was out of time as much as you say there is little chance it would have even run. It's running rich and can't get air with all the symptoms you gave us.
 
Before you tear it apart it's probably a good idea to check the crankshaft endfloat for a possible worn out thrust bearing, as that could be a cause or contributor to a failed timing chain, guides, or tensioner.
Hopefully it's OK, but these have been known to fail on the BF150.
Easily checked by gently prying under the crank pulley.

Bob
 
Topcenteronepiston.jpg

OK, It has been a bad week at work and finally settling down and back to this engine. Pulled the valve cover again and used a screwdriver to measure number 1 and get top dead center. I took a picture of the two cam sprockets. The right sprocket seems to be inline with all four cylinders position according to the service manual, The left one is off by 20 to 30 degrees on all 4 cylinders. I havent pulled anything and will takle this weekend if that is the path I need to take.
 
Back
Top