cranks/no start unless

dick strough · Mar 28, 2019

Had this 01 Laramie 360, 160k mi. for a yr. Before that my newest truck was a 67 chevy so I'm not familiar with all the sensors,relays ect. Today truck cranks but won't start unless you squirt gas in carb. Runs, idles fine. Shut off, may restart 2,3 times then have to squirt gas again. I was told it's probably not the fuel pump, but the pump not getting a message to pump until it starts. I looked in the no start threads but didn't find this exact problem. Thanks,****

jessyj · Mar 29, 2019

Ya that's not a carb its a throttle body. And I would say the fuel pump is shot.

DodgeTx · Mar 29, 2019

See if you can pull any codes with the key on key off method, a fuel pump online is about $35, cheap thing to rule out that could potentially solve your problem.

dapepper9 · Mar 29, 2019

Well when you turn the key on the pump will prime and this will emit an audible buzz.

Just turn the key on and see if you can hear it prime, door open helps. This will decide whether you start looking at sensors or the fuel pump

DodgeTx · Mar 29, 2019

^This works^ Helped me on another vehicle, ended up having a bad sensor not allowing the fuel pump to "Prime" new sensor started right up.

dick strough · Mar 29, 2019

Going to ck for the pump buz and key codes now. Where is the pump prime sensor located?

dapepper9 · Mar 29, 2019

The sensor that would possibly be at fault is going to be the cam position sensor which controls injector timing.

Big thing to start with is see if its priming. If it is, your injectors likely aren't firing which is where the cam sensor comes into play

dick strough · Mar 29, 2019

Turned key on, heard buz for couple sec. Repeated heard buz again so tried starting. Started right up. Waited 5 min, started 4 times then just cranked. Turned key on , heard pump turned on off 3 times, started. Seems when I turn key on/off at least 3 times and each time I hear the pump(have not failed to hear pump each time) it starts. Would that be fuel pressure problem?

dapepper9 · Mar 29, 2019

That's great news and narrows it down well. Sounds like the pump isnt maintaining pressure and the regulator is part of the pump

dick strough · Mar 29, 2019

Pulled the pump relay in fuse box under hood. Turn key on ,no pump sound. plugged back in get pump sound. So need to listen for pump sound each time I try to start. It has not failed to start as long as the sound is there. Could be intermittent relay?

dapepper9 · Mar 29, 2019

Doubt it. I think the regulator just isn't able to maintain pressure.

If you get it started by priming it a couple times does it stay running or die?

dick strough · Mar 29, 2019

Engine starts, idles, and runs normal after couple squirts of start fluid. I got a fuel pressure gauge today and will be using it first thing tomorrow.

dick strough · Mar 30, 2019

Installed fuel gauge. Turned key on, registered 48lb. Started, kept a constant 49-50lb. There are 6 other relays just like the pump relay so I swapped the fog light relay to the pump. See what happens.

DodgeTx · Mar 30, 2019

Sounds like a bad relay or pump failing, I'd order the pump as a cheap safety measure. Then youll have it when you need it. Get some deep sockets for the tank straps and disconnect lines and wiring before dropping tank.

dick strough · Mar 31, 2019

Yes, original pump with 160k probably time. My driver is a restored 81 cj7 I bought new, so Iv'e got a good backup! Rained all day yesturday 40 deg. Last night dropped to 31, got 2in. heavy wet snow. This morning 24deg., didn't garage truck, couldn't get in, doors froze. Sun out now, started right up. I'm starting every 1/2 hour to see what happens or don't happen! Thanks, ****

dick strough · Apr 3, 2019

Been starting fine till today. Cranked,no start. Hooked up pressure gauge, cranked a steady 50lb. Ck'd codes : 0340,1282,1391. Was told the 0340 was crank sensor,and could cause the other codes. Will let you know what I find!

dapepper9 · Apr 4, 2019

**** strough said:
Been starting fine till today. Cranked,no start. Hooked up pressure gauge, cranked a steady 50lb. Ck'd codes : 0340,1282,1391. Was told the 0340 was crank sensor,and could cause the other codes. Will let you know what I find!

0340 is intermittent loss of cam signal which can cause the issues described and is the very sensor i mentioned earlier actaully. P1391 is loss of crank OR cam signal, it'll get thrown if either one is bad. The P1282 is accelerator position voltage which is going to be TPS but definitely could be due to the cam signal loss.

Cam sensor is an easy change though, just remove the cap and rotor and its right there, goes in 1 way

dick strough · Apr 4, 2019

Thanks dapepper9 and the rest of you motor heads for staying with me on this. I spent time this evening trying to remove the gnd wire in front of one of the crank sensor bolts. Couldn't break it loose, let alone get to the crank sensor bolts. If you hadn't helped on the codes, I would still be trying. I'll see if our local Napa has the cam sensor Fri. Thanks, ****

dapepper9 · Apr 5, 2019

It'll likely be called a pickup coil like shown here. Cam sensor is just what everybody else calls it

dick strough · Apr 5, 2019

I didn't get the pickup coil today. My cap screws were froze and I managed to twist one. The inside contacts were half gone, rotor same way. Two terminals on cap top were white powder. Looks like this truck has been neglected since day one. I wasn't sure about pulling the distributor so I tried to drill out the screw leaving it in. Big mistake , broke drill off flush, now will pull. I used one screw in the new cap and zip-tied the other. I just wanted to see the difference with the new parts. Definitely smoother, will get plug wires also. Hasn't set any codes yet, there is always tomorrow. May continue truck work Monday as top is off the cj and gona be warm and sunny

****

cranks/no start unless

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