Engine stubbles at idle speed

[Gjac]

The MH in my signature has become Ihard to start and falls flat when I give it the gas. The problem seams to be progressing. Changed fuel filter before trip, ran can of seaform. Still does it when it's hot. Runs normal once im driving.

[wildmanbaker]

I may be miss remembering, but isn't there some small screens in the TB before the injectors, or on the inlet to the spraybars? One of these may have something in them causing the problems. All of the replies are plausible. This really a problem when out on the road. Remember, think electrical first, then fuel.

[Gjac]

sjholt wrote:
Possibly a bad TPS? Throttle position sensor?
You can do a resistance check to check operation?

Skip H.

. I checked this yesterday voltage goes up when throttle is opened so it seems good.

[Gjac]

I found a loaner kit after much searching and tested the fuel pressure and it was 15 psi so the pressure is good so fuel pump should be good. I usually idle at 20 in of Hg it idles now at 16 does that indicate any thing?

[sjholt]

Possibly a bad TPS? Throttle position sensor?
You can do a resistance check to check operation?

Skip H.

[DryCreek]

Just a wild guess on my part, but the OP did mention a *full tank*. Did the problems start shortly after topping off the tank?

Bad gas?

[enblethen]

I sent you a PM. The first one didn't take. look at second one.
Bud

[Gjac]

rjxj wrote:
When checking the fuel pressure it could be low but doesn't always mean it's the pump. That's just one step of the trouble shooting. As you are doing, be sure it's getting enough voltage back there. If low it could be any number of things from corrosion to a bad switch relay etc. It seems you would also have lower voltage output at idle from the alternator which could make things even worse. On an older vehicle you could have corrosion growing far back up a wire under the insulation.

Just like an o2 for example. It doesn't mean it's absolutely the o2 sensor, it can be anything in that circuit. I have fixed a couple heated o2 sensor codes by simply removing and reinserting the fuse in the power center. The ecm picked up the resistance of the dirty oxidized fuse blades.

. After looking at that video again on checking fuel pressure on a tbi my son noticed that it was a HF kit I call HF after striking out at oriellys they said they had them but when I looked at it it did not have the adaptor. I showed the mgr the picture in the video and he told me they sold them 4 years ago. How would I make sure there is voltage back there? Would the tank have to be dropped to do this?

[Gjac]

mike brez wrote:
Some reading on how things work Here

Gary hope you can get this figured out.
I'm just throwing stuff out there but I think there is a check valve in the tank called a fuel pump pulsator that will cause a hard start and stumble.

. Can you get to the fuel pump pulsator without dropping the tank? Remember I am stuck in a Walmart parking lot.

[mike_brez]

Some reading on how things work Here

Gary hope you can get this figured out.
I'm just throwing stuff out there but I think there is a check valve in the tank called a fuel pump pulsator that will cause a hard start and stumble.

[azrving]

When checking the fuel pressure it could be low but doesn't always mean it's the pump. That's just one step of the trouble shooting. As you are doing, be sure it's getting enough voltage back there. If low it could be any number of things from corrosion to a bad switch relay etc. It seems you would also have lower voltage output at idle from the alternator which could make things even worse. On an older vehicle you could have corrosion growing far back up a wire under the insulation.

Just like an o2 for example. It doesn't mean it's absolutely the o2 sensor, it can be anything in that circuit. I have fixed a couple heated o2 sensor codes by simply removing and reinserting the fuse in the power center. The ecm picked up the resistance of the dirty oxidized fuse blades.

[mike_brez]

Gary on mine when I turned the key on you could hear the pump in the tank run.
I thought the way it worked was when you keyed on it started the pump and once started in 20or 30 seconds the oil pressure switch took over and if you were to lose oil pressure the pump stopped. Not 100% shure but that's how I thought it worked. I'm shure someone with more no how will chime in.
If you want to change your pump when you get back I have a motorcycle Jack that helps a lot. The less fuel the better.
It's only four bolts and two straps holding it up. I can give you a hand if you want.
We are out right now and will be back on the 23rd.

[enblethen]

West to Moses Lake is Agri Fix. They work on MHs. 509 765-1315

[Gjac]

New relay clicks but still can't start without stepping on pedal. Tried to buy an adaptor for fuel test but O Reilly's did not carry it. I am at a loss of what to do next. It is Sunday so shops would be closed. Does anyone know of a shop that will work on MH chassis. in Spokane Wa?

[Gjac]

I found 12 v at the wiring harness between the two small spade connectors but when I connect the harness and hold relay in my hand I feel no clicking. So back to oriellys for a new relay.j

[enblethen]

Earlier models with mechanical fuel pump had a single wire oil pressure sending unit.