Ok, drove the truck for about 100 miles Tuesday, and about 40 miles Wednesday, Thursdays morning truck cranked but zero start. Attempted to cranked it over 3 times with very strong turn over but no start up. Seems like no fuel or spark. Where do you guys think I should start diagnosis, I was thinking fuel pressure gauge check? The truck was running like a champ, so this is very usually and strange to me.

 

Travel with test gear and test when it cranks but won't start:

1. Fuel pressure leak down
2. Spark at the plugs

George

 

Only because it is so easy to do, I'd recommend swapping the relays for the fuel pump and a less used item such as the rear defogger in the fuse box under the hood. I found my fuel pump relay had contacts that were extremely worn.

I had had a few random crank/no-starts that stopped when I did this a while ago.

However, I did have a crank/no-start a couple days ago. After waiting an hour or so it started fine. I plan to replace the fuel pump as a preventative measure.

 

Okay I finally got a chance to do a quick troubleshoot. Same problem no start good crack. checked for fuel pressure at plenum. Gauge read zero when crancked. Swapped the relay to no avail.

I figured it was pump related so I removed the clam shell under the tank and with a rubber hammer banged on the tank while my wife cranked the engine. After 30sec the truck turned on. It idle for 20min and I could turn off and on. The gauge now reads 60psi during crank and 55 after off. It stays at 50psi after 1 hour of being off. 🤔🤔🤔

Bad pump or fluke? I'm afraid to drive it now in fear of it leaving me stranded. I never used let the truck run below 1/4 tank and it only has 77k miles. Is it time to replace??

 

You either preturbed a marginal electrical connection or gave the pump CPR. Check your wiring/connections/ground and if OK consider a new pump. AC Delco or Delphi only. In the meantime travel with your rubber mallet (or sledge hammer depending on where you get stranded). lol.

George

 

Good job on using the hammer.

I started carrying my rubber mallet around but had no more no-starts since the one I mentioned above. I have been keeping the tank over 1/2 full.

I'm getting my new pump tomorrow and am thinking of installing it right away since it is 25 years old and has 165k miles on it.

As for your pump, although it has only half the miles of mine, it is of a similar age.

 

Goerge, Your not kidding. Im going to drive around locally until im more confident it wont die. I just dont want it to stall on me on the interstate while im commuting to work. Being winter in the midwest it makes it harder. Will look at the connectors and wiggle them around and see if anything happens while running.

Christine, Im going to start looking into a new pump. The ac delco or delphi might be harder to come across at autoparts. I want to make sure I have it at hand if the pump start to act up again.

 

You can get your options on Rock Auto

George

 

This is from where I'm getting my new pump delivered tomorrow!

 

My Blazer is also giving me a very random "cranks fine, but no start" issue. Every time I have checked for pressure at the test port; have pressure but no gauge with me.
I have pulled the fuel pump relay, and put it back in. Still no start.
But then after a few more tries and checking the coil wire, ignition module connector, wiggle various connectors, the engine starts, runs fine. Then it has no problems for a couple of weeks, then "rinse and repeat".....
The third time this happened, I was at home. Checked fuel pressure, good 60psig. Pulled coil wire from distributor cap....good spark. Put it back on....engine started just fine and continues to do so.

For the heck of it I swapped the fuel pump relay with the fog lamp relay. Been about a week now, still starting as normal.
Time will tell...................