chastings

Just thought I’d update. Huge thanks to Ohm! The return line was clear but the vacuum can for the FPR had ruptured and literally flooded the intake manifold with fuel. The regulator was replaced, the intake was siphoned dry and the oil has been changed (the crank case probably had 3 quarts of fuel mixed with the oil. I’ll change the oil again after a few hundred miles but the truck is back on the road. Thanks, everyone!

I did test it today and it showed 40psi at the Schraeder valve when cranking, but no idea how much was going through the vacuum line. I removed The fitting to the intake, cycled the key and fuel literally sprayed out of the vacuum line.

I suppose I need to replace the regulator before going any further as well

So, there’s still some gas in the intake manifold but won’t start. What else should I check? Are there any sensors that could’ve been damaged from raw fuel filling the intake?

Haha, son of a b*@ch! It’s pouring fuel from the regulator into the intake through the vacuum line.

Ok, thanks. Voltage during cranking at D1 is between 10.7-11.0 volts also, this is bizarre, but I opened the butterfly to squirt starting fluid into the intake and the intake is half full of fuel (I assume). The truck won’t sneeze or fire at all.

Nope, this is an earlier 87 and does not have the resistor

I did these yesterday, yes the rockers are moving and there is compression. At this point, guessing it sounds different (big guess) because there’s no fuel being squished in the cylinders. If working on the block ground and fuel pressure checks but still won’t start, I’ll tow it to the local Jeep mechanic. Everything seems correct but it could be something with the fuel pump or timing. strange, it literally went from running perfect to running on basically half the motor and then not wanting to start at all.

I have not, I don’t have a tool to test it. But it seems to put out adequate fuel. I can open the schraeder valve and fuel sprays out. Additionally, there’s a strong fuel smell each time I cycle the key. After replacing the fuel filter, the first time I cycled the key there was fuel coming out from the filter outlet. I had to retighten it even more. At this point, it appears to be getting plenty of fuel but I could be wrong. Any recommendations for a gauge to check fuel pressure on a 4.0?

Ok, so, I‘ve replaced the spark plugs and verified that they are firing by grounding one against the rocker cover. The truck does seem to sound different than it used to (can’t describe it) when it cranks. It seems fast but gives no indication it wants to start. Also, I smell gas but the plugs seem dry when I removed them for inspection. I guess I’m going to work on the ground at the dipstick to see if I can get it closer to 0 ohms (currently almost at 4.0). also, should the crank sensor generate 8.0 AC volts?

Ok, so, I’ve done cruiser tips 1-5 (excluding 4). 4 was not done because the truck is not at the house and I didn’t have any torx tools with me. Additionally, I put the timing light on the truck and I do appear to have spark (so 4 may be a moot point anyways). I double checked the crank sensor and it’s basically .8 ac volts i double checked the sensor grounds and they’re steady at 3.9 ohms

Thanks! I’ve actually performed 1, 2 and part of 3 so far but ran out of time. I noticed I could smell gas and there is fuel pressure at the rail as well. I’ll finish up tips 3, 4, and 5 and follow up

I'm having issues with my 87 4.0 Comanche and not sure where to start. It has spark and seems to crank relatively fast. I started with the crank sensor but not sure if I tested it right. I probed the + from my voltmeter to the red wire and the - of the meter to the white (coming off the cps). When cranking it basically shows .8 volts (which seemed high). It was running fine when I pulled out of the driveway but it needed power steering fluid. I turned it off, topped up the fluid, fired it back up and it immediately felt like it was running on only half the motor. I pulled it back into the driveway and it wouldn’t restart. Curious where else I should look. Thanks

Thanks cruiser. I've done 1, 3, 4 and 7 over the last 3 years. I did the ground refreshing when this first came to light late last year. I'll probably swing by my local Chrysler dealer and get a cps from them.

Mine has a center belt added to the existing bolts. As others have already said, very easy and a non issue. I had mine recovered last year by a local shop. It's nothing fancy, I think it was maybe 125.00