There's a problem here. 63psi KOEO is fine, provided the pump is good. Leakdown to 40psi is unacceptable. Checking pressure at the service port shows the LOWER of regulated fuel pressure, and fuel pump maximum output pressure. It also shows total leakdown in the entire system, and can not be used alone to determine where the leakdown problem is. This link explains how to check the fuel delivery system: https://blazerforum.com/forum/2nd-ge...eakdown-88305/ Post all 4 readings and we can analyze them for you.


EDIT: GM does not publish any "engine running" fuel pressure specs for this system. All tests are done with the engine off.


The P0740 indicates a circuit problem. When the ignition is in the RUN position, before the engine is even started, the problem was detected.

 

Oh captain my captain, our friends at Chilton give that spec. They say the KOEO range is 58-64 psi and engine running (at idle) pressure should decrease by 3 to 10 psi. Stuff like that is why I bought a set of factory service manuals.

 

Yet another glittering example of why NOT to use Chilton/Haynes manuals while working on vehicles Totally incorrect information on both counts.

 

true dat

 

Thanks for the link, Captain Hook! Vehicle specific info like that is why I came here. I'll put it to use, although I'm sure my wife won't be happy that I'm rechecking something I told her was fine, lol. I'll also tell any customers at work having fuel system problems with these engines to check it out (I work at an O'Reillys).

I didn't get the specs from a Chilton/Haynes manual, I got them off the computer at work. No clue where they get their data from, but it's usually just as worthless as them. The only thing the repair/vehicle info data on the computers at work is good for is looking up fluid types and/or capacities.

I rechecked the codes after I made my previous post, and I was right, the P0740 is present. So I'll have to dig into that. I'm hoping it's easily fixed. I have this sinking feeling that someone unplugged the lockup solenoid to mask a larger problem.

And here's a free tip: For GMs with the o-ringed thread-in fittings on one or both ends of the fuel filter, O'Reilly's sells a power steering line repair kit that is much cheaper than the Dorman (HELP) fuel line repair kit. It has the same fitting, but with a larger hex on the nut, and is only about 6-8 inches long, instead of ~18 inches like the Dorman. But it is significantly cheaper and works perfectly. I used it on my '90 C1500 to repair the feed line between the tank and the fuel filter when it sprung a leak. I don't remember the part # at the moment, but I'll get it.

 

The P0740 is an electrical issue in the solenoid circuit, not necessarily the solenoid, although it could be. The electrical harness connector on the right side of the trans pan occasionally has issues with not latching, causing a poor connection. The harness itself has also been known to have problems inside the pan. Following the steps in this flow chart will take you to the problem: https://blazerforum.com/forum/diagno...plained-28391/


The fuel filter fitting mentioned in the link in post #11, is $4.99 and made by Dorman. Is the power steering fitting you mentioned less expensive?

 

And again, thank you for the link! I'll check that out.

I haven't told my wife about having to recheck the fuel system yet. Not sure how that will go. My parents stopped by today and we showed them the Bravada. I was embarrassed when it took me a few tries to get it started, so I know the wife will get pretty aggravated with it's reluctance to start after sitting a while.

As for the fitting, I apologize. The fitting I was thinking of was the Dorman 800-153, which goes for around $15. I was out of the auto parts game for several years before I started at O'Reillys, and forgot about the 800-170. I should have known better and checked the numbers you listed. The store I work at doesn't carry the 800-170, just the much pricier 800-153. The O'Reilly's fitting I was talking about is the MasterPro 39108, which is essentially the same as the Dorman 800-170, and is priced the same, so I guess you could consider it an alternate to the 800-170. My store carries 3 of the MasterPro 39108 in stock at a time.

 

Wow, has it really been a month since I posted last? And the Bravada still isn't running? Guess that's why my wife's getting irritated, lol!

Been busy with work and other stuff and haven't gotten a chance to mess with the Bravada much. I never did isolate the fuel pump and check the pressure again. But I did remember something that I forgot to mention. When I originally tested the fuel pressure, I noticed that it takes several key cycles to get the fuel pressure up. And by several, I don't mean 2-3 cycles, I mean roughly a dozen or so cycles. I'm thinking fuel pump at this point, but I can't help but think that the injector "spider" could do it too. I know, I know, I should just redo the test like Captain Hook said, but the significant amount of key cycles required to get the pressure up made me wonder. I didn't remember this until I tried to start it and move it while mowing the other day. I didn't count the exact number of key cycles, but it's right around a dozen.

 

Sorry for the 5 month plus bump and the double post (wait, it's a triple!), but I wanted to bring ya'll up to speed.

It turns out the starting issue was the fuel pump. I was able to borrow a Snap-On fuel pressure test kit from a coworker that included an adaptor that connected directly to the fuel filter outlet. It took 4 key cycles to get above 50psi because the pressure bled off so quickly. Low funds kept me from buying the fuel pump until a couple weeks ago, but I finally did and it fires up every time. Well, it did anyway. #@%*ing starter died 6 days later.

I still have a couple of issues to resolve. I still haven't dug into cause of the p0740 code yet. We've only been driving it around town until that's fixed, and in case any other problems arise. For instance, sometimes it runs rough at any engine speed, and at other times it does what I can only describe as surging while moving at any speed above 25-30mph. It feels as if you're rolling into and back out of the throttle in a steady rhythm, only you're not. It has done this "surge" while stopped and idling which leads me to believe it's an intermittent missfire. The only codes stored are the P0740 and another for the right-front wheel speed sensor. It has new plug wires, cap and rotor, but I still have one plug I have to change. Someone put a washer-seat plug in the #4 cylinder and it's the only plug that will thread in, despite having the same thread size and pitch as the correct plug. Hopefully a thread chaser will fix that. I haven't changed the fuel filter yet, but I did drain, clean and refill the tank with fresh gas when I changed the pump, so I doubt it's contaminants in the tank.

*Sigh* I'm really trying hard to no regret buying this thing, lol. But for $700 bucks, I guess it wasn't too bad of a deal. At least it's rust-free!