Desperate For Help Diagnosing Why Truck Won't Start

[zayas]

Wife's truck in the driveway and it won't start. Haven't done much more than routinely maintenance oil/filter,air filter, brakes, & rear shocks. Nothing around the fuel system. Last week wife ran a few errands and on her third stop the car won't start. The engine turns over but won't start. It was during a rain storm so I suspected something got wet as the car finally started after 5 tries later (in a 3-4 min span). Two days later same sort of thing; after a few errands and car won't start the finally it does after 5-6 tries it fires up and all is fine. Well today it does NOT start but luckily she's in the driveway and I'm trying to figure out how to diagnose the problem.

 

Unrelated to this incident is the engine light has come on and off for the last year. Codes P0325 - Knock Sensor, Bank 1, and P0158 - Rear O2S, Bank 2. Needless to say I haven't done a thing to fix that either. So could this at all be related?

 

She's been running the gas tank low the last two times before filling. Since I never changed the fuel filter I figure that's would be a good place to start. I'll see if that tells me anything. Any thoughts on what else to check would be greatly apprecated. Thanks.

[Pezzy]

I had the same issue when my fuel pump relay went... I had some issues starting on a couple occasions, but was later able to start it, until it went kaput. The relay is under the hood, in one of those magic black boxes

[zayas]

I had the same issue when my fuel pump relay went... I had some issues starting on a couple occasions, but was later able to start it, until it went kaput. The relay is under the hood, in one of those magic black boxes

 

Thanks, Pezzy but no go. I just replaced the fuel pump relay and it stll won't start. I guess I will try to replace fuel filter and see if that tells me anythng. The gas tank is full so I think I got to figure out how much gas I'm willng to spill on the driveway. I thought I read somewhere that it's best to change the filter on a low tank. Wish me luck.

 

Any ideas of what to check or replace next? Thanks.

[Simon]

Before getting into that. See if you can feel pressure/pulsation in the fuel lines while someone tries to turn the truck over. If you do, the filter most likely isn't your issue.

 

Are you sure you're getting spark? Maybe your distributor is shot?

[k9sar]

engines basically need only 3 things.... air, fire and fuel... al at the right time. Check each thing for the basics first. Do you have fuel? If you can't test the pressure int eh line, crank a few times then pull a plug and see if it's wet with fuel or dry. Chances are that it's not the air that's the problem. Typically, those issues cause poor running, not non-starting. Other is spark. Now that you have a plug out, ground it against the block somewhere and crank a couple times to see if you have spark.

 

If all 3 present, now go into the next level of diagnostics... is tha spark strong? Is the fuel pressure high enough for the injectors? is the timing f-d up for some reason? Does your brain have the spark advanced so far due to a bad sensor that it doesn't fire at the right time?

 

There are fairly simple things that you can check before throwing time and money into replacement parts that you may or may not need.

 

Good luck

[zayas]

engines basically need only 3 things.... air, fire and fuel... al at the right time. Check each thing for the basics first. Do you have fuel? If you can't test the pressure int eh line, crank a few times then pull a plug and see if it's wet with fuel or dry. Chances are that it's not the air that's the problem. Typically, those issues cause poor running, not non-starting. Other is spark. Now that you have a plug out, ground it against the block somewhere and crank a couple times to see if you have spark.

 

If all 3 present, now go into the next level of diagnostics... is tha spark strong? Is the fuel pressure high enough for the injectors? is the timing f-d up for some reason? Does your brain have the spark advanced so far due to a bad sensor that it doesn't fire at the right time?

 

There are fairly simple things that you can check before throwing time and money into replacement parts that you may or may not need.

 

Good luck

 

Thanks to you and Simon for pointing in the proper direction. Some dumb question or two. I can hear the fuel pump buzz for about 4-5 secs before shutting off, however, I couldn't feel this pusling of fuel lines when cracking the car. Probably because I don't know where to check for pulsing. I thought the fuel rails running along the back wall but now am not sure. Can someone enlighten me.

 

I pulled a plug after cranking, they were dry and did get a spark. I looked at the dist cap and it looks in shape as do the wires. Wiped off slight oxidation on contact points of cap. Thought the rotor looked ok, too.

 

Now to figure where to go from here. Strong spark or not. How to do I determine that? fuel pressure high enough? Thanks.

Edited September 19, 2007 by zayas

[k9sar]

The fuel rails run under your intake manifold on top of each cylinder head. As for strong spark.... bright is good, wimpy reddish is weak. Chances that all your plugs are shot at the same time is not likely. I'm not sure what your ignition ssytem is like with respect to coil, distributer, etc but I know I did fix a jeep with a small flat stone when we were out wheeling one time. The contacts in the distributer had deposits built up on them and the top of the rotor was not making good contact with the dist cap. A little filing and the slight bending of a contact plate and she fired right up.

I have a FSM for the 99's... I'll go take a look to see if you have a pressure test port on your fuel rail. A dry plug could be due to no fuel or good spark (burns it but at wrong time) but I would suspect sputtering if you had any combustion. I'm leaning toward the fuel delivery system. Perhaps the pressure regulator is shot and you are just backflowing gas to the tank and not holding enough pressure to run the injectors.

 

... heading off to my cache of FSM's to find the 99.5.....

[94extreme]

check your plugs. these engines will run until the plugs are almost completely gone.. then all of a sudden, they don't want to.

 

to check for fuel, there should be a schroeder valve in the rail somewhere.. depress it and if it squirts, you're good to go. (tach your eyes)

[k9sar]

I didn't see an indication os a pressure test port on the fuel rail but that doesn't mean it's not there. You're in luck though (unlike my Dodge). Your fuel pressure regulator is NOT in your fuel tank. It looks to be right out there on top of your intake manifold. you should be able to pop the fuel lines off (release the pressure first) and test it. You should be able to throw between 34 and 45 psi into the regulator before it allows flow through. If less than 34, it's shot and there is not enough backpressure for your injectors to work 9the regulator is downstream from the injector set)