It just won't start

Ok, I know by the title of the post you are probably assuming it's the fuel pump first off, because when it happened that's what I thought it was for sure, but it's not.


I wasn't exactly sure what to search for either, because I figured it would mostly bring up fuel pump and ignition switch threads.

Here's my problem. I was driving my blazer today, on a little bit of a road trip. No problems to speak of throughout the whole day, run like new. I was cruising along in fifth gear and then all of a sudden I lose power, the engine just up and quit.

I have it towed to my sisters house, and then I get to take a good look at everything. About a year ago I had changed the fuel pump in it, and was expecting that to be the problem. So, I didn't really know what to think when I turned the key and could hear the whirr of the fuel pump.

Since I had recently changed the spark plug wires, distributor cap, rotor button, I proceeded to check all that stuff out. Getting good spark from everywhere, so none of those seem to be the problem either. Oh yeah, checked for fuel pressure at the engine and had plently of that.


So, I have fuel pressure, I have spark. When I crank it, it doesn't hit a lick. I get a can of starting fluid just to see if I can get it to hit, and it works, it starts and runs for a second or two until the starting fluid runs out.

The problem now seems to be fuel related. I don't know where to start though. I am gonna try the fuel filter, even though I'm 99% sure that won't help since the one in it is fairly new, but I have one already so it won't hurth anything to change it.

What could my problem be? I know there is fuel pressure at the motor, I know that there is spark, I know that it has the ability to still run even if it is just for a few seconds. It's as thought the injectors themselves have all decided to quit at exactly the same moment in time.

I need to have a good idea on what to look for before I go back, it's sitting at my sister's place right now, which is a good two and a half hour drive away. If I can't get it started there I'm gonna have to rent a tow dolly and haul it back, and I don't look forward to that long a drive with a tow dolly.

I really appreciate any help that anyone can give me. I know the post was a little long winded, but I wanted to make sure I described my problem fairly well.

Sounds almost completely electrical in nature. Have you checked your fuses yet? Also - might be a short/broken wire in the ECU harness leading to your injector(s). You'll have to rent or purchase a noid light to make sure that they are getting a signal to "fire". If there is a positive indication that the ECU is still working and the noid light reveals that your injector(s) are getting current, then backprobe with a VOM through the wire harness going to the injector assembly and make sure that they are within resistance spec. Please refresh our memories on what model year and style engine you have so we can help more?

You know, when I wrote that I was almost certain I put the model year and such in. I thought about it anyway, looks like it slipped my mind though.

It's a 2001, 5-speed, 4-wheel drive.

I've already checked all the fuses as well, it was actually the first thing I went through before I had to call a tow truck.

With a truck that new, I am almost certain to blame the battery... they go about 5 years or so and then start getting weak. Try charging it up with a charger or using a booster battery to turn it over, before anything else.

I guess I forgot to mention that as well.

Late last night I switched the battery out, and it still didn't help out any at all. I had spoken to someone and the suggested the same thing, so I gave it a try. Still the same old thing.

Again as mentioned, check for injector pulse if none the injector fuse could be bad for some reason, or the cam sensor in the distributor, or is this a coil on plug engine. A scan will tell you if the cam sensor is working, again to need to check for injector pulse.

Do you have an alarm on it? Is the security light on or blinking? What was the fuel pressure when you checked it?

Do you have an alarm on it? Is the security light on or blinking? What was the fuel pressure when you checked it?

I don't remember the exact number of the fuel pressure reading, I was so tired and aggrevated last night that I just didn't pay it much attention. I wanted to see if it had pressure mainly, any pressure at all. Seems like it was between 50 and 56 lbs, but I don't know how good those readings are, gonna have to recheck it and see. It just about has to be a clogged fuel filter, or the fuel pump is just going bad.

It doesn't have an alarm, nor does it have a blinking security light.

I rented a U-haul tow trailer today and got it back to my house so I can do some actual work on it now, and tests everything thoroughly were I'm not rushing to get it done.

Nothing is more aggrevating than have one just quit with no warning. Also, nothing is more aggrevating than having a Haynes manual and reading in it that it needs to be taken to a qualified mechanic or dealership to have something checked (injector resistance). Buy those books because we want to work on them ourselves, not be told to take it to a mechanic.

Yeah, you'll definitely want to recheck the fuel pressure. Those numbers are low. The pressure should be:

Key On Engine OFF (during the intial 2 seconds when the fuel pump is running - 60 - 66 psi

Key On Engine OFF (After the fuel pump shuts off) - 55 - 60 psi (This number is to determine the integrity of the system. It should hold that pressure and not bleed down. If the pressure bleeds down it means that there is a leak in the system.)

Key On Engine running it should drop 3 - 10 psi


Here's a little info about the 96+ system and their need for fuel pressure:
http://www.automotiveforums.com/vbulletin/showthread.php?t=450484

I was way off with the pressure reading. I used a borrowed guage, mybe the numbers were diffrent, or i was just really mad.

It reads 18lbs on my guage, which i trust, with no bleed off. Pump sounds normal at key on. Brand new fuel filter, battery, almost new alternator (2 weeks).

Ideas? Maybeloose connection at pump? Changed pump andconnector about a year ago.

Well, with 18 PSI, there's no more guessing as to why it won't start. I would check the pressure at the filter, this will narrow down which end is the problem. If the pressure is good at the filter and bad at the schrader valve, then your looking at a leaking injector or bad regulator. If the pressure is bad at the filter, it could possibly be a bad or loose connection, damaged wire, etc. It may also be a split pulsator, or a bad pump.

Dunno if it makes much difference, but I get 12volts at the fuel pump connector. So that much is now ruled out.

Dunno if it makes much difference, but I get 12volts at the fuel pump connector. So that much is now ruled out.

What is the battery voltage?

You never said but if CFI injection, bad fuel pump. Not enought pressure, but even with TBI or MFI injection not enough fuel pressure.

What is the battery voltage?


It's just a hair over 12 volts.

So was the reading at the pump, they were very close, within a tenth of a volt for the two seconds it would read when I had someone turn the key on.

I'm thinking the next time I get a chance to work on it I am going to check the pressure right at the fuel filter, then make up my mind on what is going on from there.

Progress!!!

18 psi at the filter.

Starting to look just like a bad pump.

Sounds like it. I hope your pump is still under warranty.

Progress!!!

18 psi at the filter.

Starting to look just like a bad pump.

Also check your battery and its state of charge, most likely it is your pump, but a poor battery could also cause low pressure.

Battery should read 12.8v+ with the engine off and 14.4+ while running.

Sounds like it. I hope your pump is still under warranty.


It is. Was hoping I'd never have to use the warranty on it, but I'm glad it's got one now.

Finally got it going, and it was the fuel pump, it just didn't go completely dead like I thought it would. The first time I changed it, the fuel pump wouldn't even come on at all.

This one was still under warranty and all, so it was a pretty cheap fix, minus the cost of towing it two and a half hours back to the house, all I can say is thank goodness for U-Haul car haulers.

I read once before that a dirty fuel filter can cause this to happen. While mine wasn't as free flowing as a new one, it didn't hardly seem clogged up terribly either. What would you say that the recommended mileage is to change a fuel filter?

30,000 or 2 years which ever comes first.

Finally got it going, and it was the fuel pump, it just didn't go completely dead like I thought it would. The first time I changed it, the fuel pump wouldn't even come on at all.

This one was still under warranty and all, so it was a pretty cheap fix, minus the cost of towing it two and a half hours back to the house, all I can say is thank goodness for U-Haul car haulers.

I read once before that a dirty fuel filter can cause this to happen. While mine wasn't as free flowing as a new one, it didn't hardly seem clogged up terribly either. What would you say that the recommended mileage is to change a fuel filter?


Recommended replacement is 30,000 or 2 years.



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Dirty Fuel Filters and Running your Gasoline below 1/4 tank will put a huge strain on your Fuel Pump. Gasoline acts as a coolent for the pump, the lower it is in the tank, the hotter your pump runs...