fuel injected gas engine only starts with starting fluid

[thegary]

I have a Zenith Power Products 420 gas industrial engine. It is a 4 cylinder Hyundai 2.0 2009 model year. It has all Bosh fuel injection components and ignition components. I purchased 2 of these motors used. I am rebuilding a chipper and will install one on it when I am done.

I hooked up a battery to both engines and started them one at a time. One fired right up and runs good but other things are not in good shape on the engine so I want to use the other one.

The one I want to use will crank and crank but not fire until I spray starting fluid down the intake. Then it starts but chugs for a second or so then catches and runs fine after that. If I shut it off I have to restart it with the fluid again then it runs fine after that.

These engines use a special diegnostic tool to read codes and data that I do not have. It seems I can find very little info on this tool.
Anyway when the engine is running there are no warning lights lit and it idles great and when I flip the switch it goes into run mode and runs great at 2600 rpms. When I turn on the key I can hear the fuel pump pressurize for a couple seconds then kicks off.

What are your thoughts? I searched the internet and found a guy that had the same problem and it turned out to be the crank sensor but that was on a Hyundai car. Does that make sense? I have to say I know very little about fuel injection.

If any of you guys know anything about the diegnostic tool for this engine and can shed some light on it I would also appreciate it.

I have to fix a bad oil leak on the engine before I can tell you if it will restart when warm without starting fluid. I am afraid to run it very long the way it is because I think it would run out of oil in 5 or 10 minutes. Someone put a huge bypass oil filter system on it and it is leaking like a siv so I have to remove it and get a new oil pan drain plug.

[FlaJoe]

On an FI engine, when you turn the ignition on the fuel pump should run for a few seconds to buildup fuel pressure and then turn off. If you don't start the engine immediately, the FP will usually run for a few seconds about every 20 seconds. But once it detects that the engine is actually running it should turn the FP on and it should run continously. It sounds like yours isn't priming the fuel system properly but does provide the run time function. You could have a bad FP that isn't building pressure fast enough or you could a bad FP control module. You may also have a bad fuel pressure sensor and the system thinks that the system is pressurized when it's not.

FP control modules are a known problem in the late F-150 trunks. They're mounted on the frame under the bed and the aluminium bodies on them corrode badly and fail. They also run very hot which is probably why Ford put them under the bed of the truck to start with.

I think your crank sensor is fine. Without it you probably wouldn't be getting firing pulses to the spark plugs and your engine wouldn't start all.

[FlaJoe]

Here's a thought, turn on the key without starting and let the FP run until it shuts off. Repeat that a few times and then try to start it. If I'm right and the FP is at least running for a few seconds then the FP should finally build up enough pressure to start the engine.

[thegary]

I will try that on friday .

[ronsii]

I usually just hook a gauge to the Schrader Valve that pretty much all FI systems have... I think you can still get the harbor freight kits for less than 15 bucks.
Sometimes the crank sensors will do like yours though, I think they get a bit desensitized and just don't pick up on slow rpms...

[thegary]

I usually just hook a gauge to the Schrader Valve that pretty much all FI systems have... I think you can still get the harbor freight kits for less than 15 bucks.
Sometimes the crank sensors will do like yours though, I think they get a bit desensitized and just don't pick up on slow rpms...

I got a HF fuel gage kit about a month ago. I have not found a schrader valve but I will look again for one. If it does not have one I am sure I can T in somewhere.

[thegary]

Well I am narrowing it down. I put a fuel pressure gage on it and when I turn the key it pressurizes to 50 lbs but when the pump stops the pressure goes to zero. When I run it the gage stays right at 50-51 lbs. I pulled the return line out of the tank and every time I turn the key and the pump runs and it shuts off I get a flow of fuel on the return. There is a manifold that the fuel line goes into that has a feed and return port on it I am thinking that there is something wrong with the pressure relief in this manifold. I am assuming it has one in it somewhere. On friday I will pull it out . If I do not find any thing obvious I will take the manifold off the good running engine and put it on and see if it makes a difference. I do not see anywhere that fuel is leaking out of the system . If it is not the return pressure valve is it possible that an injector is stuck open? If it were I would think the engine would have at least poped when it burned the fuel that leaked through . Also when I start it on either it runs great with no mis or any problems so I doubt it is an injector.

On a side note there is no MAF on this engine and as of now I do not see a MAP sensor either. I thought EFI had to have one or the other or both to work. If I am not mistaken the MAP sensor should have a vacuum line conected to it and I do not see any vacuum lines going to the intake area at all.

[thegary]

After some internet search I see that there is a fuel pressure regulator on EFI engines. I believe it is what I was seeing mounted on that manifold block I was talking about . I believe this is the culprit . I am going to swap the whole manifold from my other engine to see if that solves the problem. Then I will pull the pressure regulator out of the suspect manifold and see if I can find a new one. It will not be the same as hyundai uses on their cars. This engine was modified by Zenith power products and it uses a lot of other stuff . From the looks of it mostly Bosch parts. The only thing hyundai is the fuel rail and the injectors. From investigating on the internet I believe the fuel pressure should be 55 lbs.

[ronsii]

55 sounds about right, most of the ford/chev/etc rigs I work on run 40-65 but will actually run at much less 15-20. my work truck f250 had a similar issue where it didn't like to start anytime it was turned off... checked fuel pressure it was 10-15 so I figured pressure reg... changed it... no different??? bad new part... changed it again... no different?? turns out the fuel system with 2 tanks does not use a fuel switch on the pressure side but instead they just tee both pumps and each pump has a check valve to stop fuel from returning to the tank(anti-backflow) both check valves were bad. since your doesn't have 2 tanks I doubt this is the problem so could be the pressure reg... they are easy to change and when they go bad*usually* there will be fuel in the vacuum line on the top of the regulator.

EDIT: sorry when I posted I had only read your last post... I see in the previous posts you mention losing pressure this could be the same thing mine was doing backing up through the pump. I guess it is a pretty common issue.

[M J D]

I really doubt it's an injector that's stuck open. You would most likely have fuel in the oil if that was the case. Sounds like a regulator or possibly the fuel pump has a built in check valve that's not functioning right.

[thegary]

Well I did some more digging today. The the FPR is whats making the pressure bleed down. I clamped off the overflow line and it held pressure but evidently this is not the problem with the no start. I kept the clamp on the overflow and even with pressure it only starts with starting fluid sprayed in the intake. after it starts fuel pressure still was at 50 lbs.

I put the fuel gage on the other motor to see what it does and the fuel pressure still bleeds town to zero in about 3-4 seconds after it is turned off. When starting it the pump cycles like the other one for a second or two then stops. I hit the key and in about 1/2 of a crank The fuel pump turns back on and it starts.

The one that does not start does not do the same thing. The fuel pump does not turn back on when cranking the engine. When I spray start fluid in it it fires a couple revolutions and then I see the pump kick on.

I am wondering if it might be the crank sensor or the came sensor not telling it to turn on.

[ronsii]

could be

[duramax-rob]

be careful with the starter fluid. could wash the oil off the cylinder walls. use a little engine oil and turn the engine over to lube the walls and rings.

[scsmith42]

Sounds like either a bad injector or a bad pressure relief valve. You’re headed down the right path.

[farmersammm]

I read somewhere that a few motors had oil pressure shutdown switches, not oil level, but pressure. But I think they were disabled during cranking. Not sufficient pressure during cranking.

I'd think the only thing that would logically enable a pump is either prime mode, or run mode (crank sensor). Crank sensor should tell the PCM that you're cranking the motor to start it. Some odball setup might have a circuit that enables the pump through the ign switch for cranking, but I doubt it.

Gotta have two things to start a motor...……..gas, and spark.

Should be a spark at crank

Should be an injector pulse at crank (don't believe you've checked this yet) (can have all the pressure in the world, but if it ain't gettin' in the combustion chamber at the right time, it ain't gonna fire)

And should be a bit of fuel pressure at crank.

[farmersammm]

Another thing...………….I dunno about your motors, but my stuff holds pressure for quite a while key off, engine off. Should prime, and hold.

[farmersammm]

leakdown test should be same for your motor I'd imagine http://www.hemanual.org/fuel_pressure_test-1455.html

[thegary]

Farmer I agree with you for the most part. The only thing is that both motors leak fuel pressure very fast when shut off. I thought they should hold pressure too. I am not done investigating that part but do not believe that is causing the no start after what I see after comparing the two engines. My next move is a crank sensor, they are about $30 so its not too bad. I have read that on some engines the injection is triggered off the cam sensor and the ECU has to read both the cam and the crank sensor to inject fuel. I also read that when these sensors go bad that it is usually at low speed rotation and will work at higher rotation speeds. That is what I think is happening. They say that it is due to them losing some of their magnetism. I believe the engine does not rotate fast enough for the sensor to start working but when the starting fluid fires and the engine turns faster that sensor or sensors work. This is just my theory with the limited knowledge I have got on the EFI systems. I am learning as I go.

What I do know is to investigate fuel pressure loss further and possibly have to replace the fuel pressure regulator . This is more complicated than it sounds. this paticular engine uses a non standard FPR and I need to talk to Zenith about this before I go and buy a new one. I know my fuel pump is good and my injectors are not leaking. I know the fuel pump does not kick back on until I give it a shot of start fluid and the engine rotates faster. If I had a noid light I could see if the injectors are firing just with cranking but I do not have them but am fairly confident I am on the right track.

[ronsii]

Can you just swap sensors across both engines on at a time? then you'll know when the good engine does not fire

[thegary]

Can you just swap sensors across both engines on at a time? then you'll know when the good engine does not fire

Yes I could and probably will for the crank sensor. The cam sensor is kind of hard to get at so if I need to change it I will go buy a new one rather than fight with 2 engines.

[ronsii]

Yeah, my powerstrokes take all of about 5 minutes to change out a crank sensor in fact I carry a couple extras in the glovebox just because they run about 20-30 bux and only last about 1-2 years. the dodge cummins just about as easy to change out the crank sensors too. oh, and I had a bad one right from the factory a couple years ago...

[thegary]

Well I swapped crank sensors and it made no difference. My only other idea is the cam sensor so I will have to go get one and give it a try. If its not that I am fresh out of ideas

[mla2ofus]

I hate it when I have to start just changing parts 'til I find the bad one.
Mike

[thegary]

I hate it when I have to start just changing parts 'til I find the bad one.
Mike

You and me both! I like to know when a part is bad . I admit I am out of my comfort zone on this motor. I will not get too frustrated though until I am out of logical ideas.

[ronsii]

Do you or someone you know have a set of noid lights??? they will show if the injectors are getting commanded to give fuel. HF used to sell em' long time ago full set of 8 or 10 if I remember right... for 20 bux I think I paid...