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BF225 Cranks, but won't start

B

Bpino

New member
I have a 2002 BF225 that had an intermittent alarm that wound up being O2 sensor. After replacing the sensor the engine ran great. Came back 2 days later and engine cranks but won't start. I pulled the plugs and checked for spark which I have. I did find them to them to have carbon build up, so I replaced them. I replaced high/low fuel filters and then hooked pressure gauge up. Turned the key without cranking and heard the HP run for 2sec. Checked the pressure gauge and had 0psi. Question I have is shouldn't I have 41-48psi at the gauge? Seems to me like the vst is not filling up enough to get fuel to the HP pump. Running out of hair to pull out, I would appreciate anyone who has any insight. Thanks

Checks Done so Far:

- Drained VST / Removed & Cleaned (Clean no gunk or debri)
- Replaced high / low fuel filters
- Bench tested fuel line cut solenoid
- Pressure check HP (0psi)
- Replaced HP fuel pump
- Ran aux fuel tank
- Checked safety lanyard
- Checked all fuses
 
I would check voltage at fuel line cut solenoid (with load) and check the low press fuel pump. Is the priming hand pump hard? If all that is ok, I would check the VST Float and VST Needle Valve for corrosion, correct operation and correct float height. Lastly the Fuel Press Regulator, but this as the last item. Did you open the VST or just drain and blow with injector cleaner spray?
 
When you say check fuel line cut solenoid, what do you mean with load? I started checking it and it does operate the plunger from a separate 12v source. Also is the resistance reading checked out to be within spec. I did have the low pressure fuel pump apart and found that the plunger needed some force to operate. I had the VST apart as well and it was clean (no residue or debri) . The float needle looked good and it did function properly when I turned it upside down and blew into it. I did not check the float height which I believe is 25-33mm. Should the fuel line cut solenoid have voltage when turn the key switch? I'm leaning toward the LP pump, but my last guess cost $360 for a HP pump!!!
 
You tried the solenoid on a bench so you know the solenoid is good but you have no confirmation that the solenoid is receiving 12V and is doing its job installed and wired to the engine when the key is turned, ie; it may not be receiving current when it is supposed to. With load I mean that many people simply measure voltage, say at the solenoid connector, with the client disconnected and this in reality is not the way because tou could have voltage drops if you have a load. It is best if you can measure voltage with the solenoid connected and, failing that due to pin acces, put an external load instead of the solenoid, in this case such as a 12V lamp that consumes maybe 1A, or a 10W or 20W lamp which will be near the solenoid current. The low press fuel pump I guess you can always disconnect the output and crank the engine with the output running to a bottle or container. The LP fuel pump is mechanical so you can test it this way. If the voltage at the solenoid connector is good with load or lights a filament bulb (not LED) and your LP fuel pump expells fuel while cranking, I would suspect the VST. VST failure can cause the engine not to start or to starve/splutter.
 
This might sound like a stupid question but is the high pressure filter cartridge the right wsy round, if not it will block fuel flow?
 
Someone may say otherwise but it will not affect your engine if you don't reset the ECU. The only problem will be that your O2 Sensor will continue to show up if you connect Dr H or pull codes. No need to clear engine learning map either
 
Correct Blacktimes, the only reason it's a good idea to clear codes if you don't have Dr H is when you have another fault you won't know what the current fault is
 
Ok, so with the fuel cut solenoid, when I turn the key to the on position and my tester is on terminal #1 & #2 (harness side) I should get between 12-13v, at the 2p connector at the solenoid, correct? The only way I get the 12v is if I test between term #1 (blk/yellow) and body ground. I checked for an open wire on the red wire, from the 12p connector at the ECU and the 2p connector at the solenoid, and I have continuity. Seems like when I replug it back in I don't have ground thru the ECU. Anyone have any ideas?
 
Before you carry on, why not bypass the fuel cut solenoid and see if the engine runs, or alternatively, put a bit of clear tube on the drain, open drain screw holding the clear tube up and see where the fuel level is.
 
Ok, I can bypass but I wasn't sure if the ECU needed to see the solenoid in the open position for other systems to work
 
Ok, so I bypassed the solenoid with no better result. Still just cranks and wont fire. I also pulled the VST again cleaned and check the float height, all within spec. Running out of ideas!
 
You need to be more specific, is there fuel in the vappur seperator ? Is there 40psi fuel pressure? If you have fuel and no pressure then there is a problem with the HP pump. If you hsve fuek pressure then you chasing the wrong issue.
 
There is fuel in the VST, but there is 0 pressure. That's what my original thought was, so I replaced the HP fuel pump. So then I went to the LP fuel pump and disconnected the return to the VST and got no fuel to discharge, so I replaced the LP fuel pump. I started to troubleshoot the fuel line cut solenoid and only have 12v when testing from blk/yellow to body ground. No voltage when testing between blk/yellow & red. So I then bypassed the solenoid and got no result. That's where I am now
 
When you say bypassed the solenoid, you mean you took the whole thing out of the circuit so that there is now fuel flowing into the vapour seperator? This description is very confusing and unclear. Just forget about the cut off solenoid for the moment and just say whether or not there is fuel getting through the LP fuel pump. If there isn't, then it's got nothing to do with the shut off solenoid. It will help a lot if we just stick to tje basics here. If there is no fuel no fuel in the vapor seperator then you need to find out why
 
Can I also explain the fuel cut off solenoid. It is there to help prevent vapour lock. I opens for 4 secs when fengine is started, then closes until engine temp reacjes 60degrees when it opens and stays open. It does not prevent fuel flow. You also mentioned the low pessure pump pluger is hard to press, this too is normal. I think you need to start at the tank and work through your fuel system and find out where the issue is
 
Agree with Ian on starting from the fuel tank and working your way forward. The 0 psi coming from the HP fuel pump is the main give-away.

A couple of other thoughts...

1. You said that you checked the kill switch. How did you do that? Can you get to it and disconnect it totally?

2. When you changed out the HP fuel pump, did you clean the screen on the bottom of the pump holder? If dirty, it probably would prevent some fuel flow and firing, but it can screw up how well it runs.

3. Do you hear the HP fuel pump run for about two seconds when you first turn on the key switch?

4. Consider disconnecting the hose from the HP fuel pump to the fuel pressure regulator, put the end of the hose in a clear container and have someone briefly activate the key switch to confirm you are not getting any fuel out of the HP pump.

5. Do the same with the LP fuel pump. Disconnect the hose from the LP pump to the VST (or cut off solenoid), put the end in a clear container and have someone briefly crank the engine to confirm whether you are getting fuel from the LP pump. If not, work backwards up the fuel line to the LP filter and the on board F/W separator.

6. If getting fuel from the LP pump and no fuel from the HP pump, then obviously the problem is with the VST or the HP pump itself, which you said that you replaced. Bench test the HP pump. If it passes, then you are back to the VST. And if that is the case, then 9 out of ten times the needle valve will be stuck closed or there is too much fuel in the VST which is forcing the needle valve closed.
 
So, I got her running last weekend after thoroughly cleaning and following the fuel system backward and it seems I might have had a blocked line. I wanted to make sure I wouldn't get any alarms, so I hooked up Dr. H and I keep getting an HO2S alarm. I reset the ECU and cleared DTC , and ran engine at 2800rpm for 10 min, then came back to idle and it came back again. It seems the HO2s sensor has failed. I have continuity between the (2) white wires. I replaced it in June and it might have 3hrs on it. What would cause this to keep failing?
 
What reading are you getting from the O2 sensor with the engine running.Remove the sensor as soon as you shat down the engine and see if there are water droplets on it. A bad exhaust manifold seal can cause water to spray up onto the sensor at idle.
 
Ian, I ran it again at 2800rpm for about 5min, then came back down to idle and it threw the code again. I pulled the HO2S sensor and didn't find any water droplets. When I first started it, the HO2S had 1.01v. As I ran up to 2800 it fluctuated between .10 to .77. In the service manual it says to check continuity between the 2 white wires of the sensor. If you have continuity it says to replace. If I did replace it I'm afraid I will have the same issue and the problem will still exist. I know there is a lot of chatter about these HO2S sensors for these engines! What are your thoughts?
 
If the voltage is fluctuating it usually means it's fine. The only thing is it usually settles at about 0.9 at idle.
Not sure what manual you are using but you should have 10-40 ohms resistance between the white wires, they are for the heater. Is the motor running smoothly at idle?
 
Well I tried another sensor and still getting the same alarm (DTC 1-4). I did notice that in a previous thread that chawk_man mentioned that high fuel pressure or an ignition coil will give the same code. So I hooked up a fuel pressure gauge and for most of the time the fuel pressure is up to 70psi. I know that it should be between 41-49psi. What would make the pressure so high? I also checked the spark plugs and there isn't any fouling what so ever. The one thing I did notice was that there was some oil in the plug well, maybe the well seals are going bad?

** The alarm goes off when I run the rpm's up to 2500 for 5min, then back off to idle and within minutes the alarm goes
 
70 psi will cause issues. On top of the port side fuel rail is a fuel pressure regulator. If you remove it you will find a very fine filter basket sitting in the top of the fuel rail. This could be blocked, or a kinked return hose from the regulator back to the vappur seperator, very likely if you had the unit off. Failing that but unlikely, a faulty regulator.
 
So I replaced the small filter basket on the pet fuel rail and checked all the lines to make sure nothing was kinked. Started up no issues until 5 min into idle, and got the DTC 1-4 failed HO2S sensor again. Checked fuel pressure again an it is still high running around 65psi. Should I replace the regulator?
 
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