Help with Fueling issue after sitting

[RustyRodder]

Hey guys,

Need some help with a (suspected) fueling issue on my 1988 4.0.  Simply put, it won't start after sitting. I turn the key, fuel pump primes, fuel is at the rail, and then turn the key... nothing. cranks, no firing.  Maybe a burp sometimes. If I spray fluid into the TB, it fires right up and idles all day, drives fine.  Turn it off, starts right back up again.

 

So far, I have done the ground refresh, C101 refresh, I did replace the pump (It stopped priming at one point, so maybe unrelated), new CPS, and put a jumper on the ballast resister. the CPS has had the TSB for the rewiring done in the past.

Looking for any ideas where to go next, beyond 'carry some starter fluid and torx'.

[gogmorgo]

Did you check pressure at the rail or just poke the valve? Simply having fuel doesn’t mean you’ve got enough volume at adequate pressure. 
The other question is how long it’s been sitting and what the fuel in the tank is like. Could be the filter or sock on the pump is plugged. I also get real suspicious of the fuel line between pump and sending unit when someone says they just replaced the pump. It’s very easy to compromise that piece, and if it gets replaced with non-submersible fuel line it’ll also cause problems. 

[RustyRodder]

1 hour ago, gogmorgo said:

Did you check pressure at the rail or just poke the valve? Simply having fuel doesn’t mean you’ve got enough volume at adequate pressure. 
The other question is how long it’s been sitting and what the fuel in the tank is like. Could be the filter or sock on the pump is plugged. I also get real suspicious of the fuel line between pump and sending unit when someone says they just replaced the pump. It’s very easy to compromise that piece, and if it gets replaced with non-submersible fuel line it’ll also cause problems. 

Just a poke- I don't have a fuel pressure gauge. 

Fuel is from last summer, 91 recreational fuel (non-ethonal).  Replaced the filter when I did the pump, along with the lines in the tank with fuel-friendly line. 
 

Its happened after sitting for anywhere from 3 months to 3 days.  Its stored at my dads, so I don't get out to it on a daily basis. I may ask him to try starting it next time after a day to see what happens.

[gogmorgo]

So sometimes it starts and sometimes it doesn’t? How does it run when it does start? 

If the fuel drains back from the line it can take a little bit to reprime it. More than a couple flips of the key at least. But I’ll reiterate on submersible fuel line. Regular fuel line is usually only fuel-friendly on a thin inner layer, with cheaper not so fuel-friendly material on the outside holding it together, and it degrades quickly when submerged. Even if it doesn’t fail completely it makes it hard for the clamps to hold it.

But we could be barking up the wrong tree, we don’t know whether you have proper fuel pressure or not. 

 

Also, if you want it to run right you’re probably going to want to run more than one tank of gas through it a year. I would also be far happier running regular pump gas that’s coming from a tank that gets cycled regularly vs your high-dollar specialty gas that’s been sitting for who knows how long before you got it. And unless you’re somewhere really humid ethanol isn’t going to be much of a concern. Honestly it might be better because it’ll pull the condensation into the fuel instead of it sitting on the bottom of your tank until it rusts out. 
But if it starts and runs sometimes, the fuel in the tank isn’t going to get less garbage on its own for you. I also have been impressed with the 4.0’s ability to run on garbage fuel. Doesn’t really seem to care. 
 

Something else worth investigating once you’ve established you’ve got proper fuel pressure when it’s not starting for you is that the fuel injector timing is controlled by the cam sensor/distributor sync sensor. If the distributor is worn out and wobbling around it screws with the timing. I think cruiser54.com might have a test procedure for it as well, but I haven’t gone and looked. 

[RustyRodder]

6 hours ago, gogmorgo said:

So sometimes it starts and sometimes it doesn’t? How does it run when it does start? 

If the fuel drains back from the line it can take a little bit to reprime it. More than a couple flips of the key at least. But I’ll reiterate on submersible fuel line. Regular fuel line is usually only fuel-friendly on a thin inner layer, with cheaper not so fuel-friendly material on the outside holding it together, and it degrades quickly when submerged. Even if it doesn’t fail completely it makes it hard for the clamps to hold it.

But we could be barking up the wrong tree, we don’t know whether you have proper fuel pressure or not. 

 

Also, if you want it to run right you’re probably going to want to run more than one tank of gas through it a year. I would also be far happier running regular pump gas that’s coming from a tank that gets cycled regularly vs your high-dollar specialty gas that’s been sitting for who knows how long before you got it. And unless you’re somewhere really humid ethanol isn’t going to be much of a concern. Honestly it might be better because it’ll pull the condensation into the fuel instead of it sitting on the bottom of your tank until it rusts out. 
But if it starts and runs sometimes, the fuel in the tank isn’t going to get less garbage on its own for you. I also have been impressed with the 4.0’s ability to run on garbage fuel. Doesn’t really seem to care. 
 

Something else worth investigating once you’ve established you’ve got proper fuel pressure when it’s not starting for you is that the fuel injector timing is controlled by the cam sensor/distributor sync sensor. If the distributor is worn out and wobbling around it screws with the timing. I think cruiser54.com might have a test procedure for it as well, but I haven’t gone and looked. 

 

It will start if I have already started it recently (I start in the morning, drive to get coffee it will restart. Let it sit for a few days, it won't start again).  Once it's running, it runs... well, like a 230,000 mile 4.0. Good.oil pressure, no sputtering, maintains 70mph no problem.

 

I usually run more gas through it, but the start issue had us driving the gladiator over the comanche mostly. Plus the fuel pump being a butt. Random thought- what if I reversed the lines coming out of the sending unit? I'm not used to return style systems.

 

I'll check cruiser for dizzy testing.

[gogmorgo]

If reversed lines was the issue it would probably be more consistent. But that’s the other thing. Sometimes it starts and sometimes it doesn’t, what’s different about the times it does? Does it fire off right away or does it make you work for it? On the days it doesn’t start is it doing the same thing, you go through the same steps and it just doesn’t?

[RustyRodder]

3 hours ago, gogmorgo said:

If reversed lines was the issue it would probably be more consistent. But that’s the other thing. Sometimes it starts and sometimes it doesn’t, what’s different about the times it does? Does it fire off right away or does it make you work for it? On the days it doesn’t start is it doing the same thing, you go through the same steps and it just doesn’t?

When it does start, its after Ive done the ether down then TB thing. Its the initial start after being cold where it just won't do it. it starts every time using starting fluid, then runs fine. if it was a carb, I would say the starting/idle jet is clogged. Ill take a video next time I am out there.

[Ωhm]

During engine CRANK, RPMs must reach at least ≈300RPMs in order to wake up the ECU. Also, engine speed (RPMs) determines CPS signal strength. Maybe problem lies with poor condition of BATTERY, STARTER or both when engine is COLD. Try CRANKING with the gas pedal at WOT, should increase CRANKING RPMs, then slowly back off throttle as engine CRANKS. Backing off the throttle or hitting ≈400RPMs will disable the Clear Flood Function used by the ECU.

[RustyRodder]

I wanted to give an update since I hate finding old threads with no resolution:

 

I replaced my 6 year old battery, as well as cleaned the relays, starter solenoid,  all the power connections, and installed the meanlemons wires that I've had for a few years. Started right up cold, no problem. 

[Ωhm]

[MeanLemons]

I’m very glad to hear that 

[cruiser54]

[cruiser54]

Hey Neal!!!!