Starting Issues

[85mustangGT]

I have read a ton of threads about starting issues but mine does not seem the same.

Fuel pressure
60 lbs key on engine off
55 lbs when at idle
60 lbs engine off after running and stays there for at least 15 minutes

Fuel pump was replaced about 2 years ago but not the AC Delco brand - those are $$$

If vehicle sits for over 8 hours it takes several minutes to get it started, I was primming the pump/lines with a couple key on/off but it appears it is getting worse.

It is worse during rainy days or humid air. I replaced the dist cap, wires, plugs and fuel filter about 10000 miles ago.
Today it took about 5 minutes of cranking to get it started, once its running it does great. I can turn it right back off and it will start back up. No dummy lights on dash except for the "Check AWD" or something like that.

What else do I need to check as I dont want to start just replacing parts?

Thank you guys for all your great help on here.

[old_master]

Aftermarket pumps have known issues with insufficient maximum output, excessive leakdown, noisy, and a short life expectancy, OEM pumps don't. That's why they're more expensive.

Have you checked fuel pressure when it's acting up? Connect the fuel pressure tester and watch it when it won't start. It should prime to at least 60psi in less than 2 seconds. If the check valve in the pump does not seal properly, excessive leakdown will occur which will cause excessive cranking or cycling of the ignition to pressurize, (prime) the system. When it acts up, try a shot of carb spray in the air intake, if it fires up, it's a fuel delivery issue. If not, probably ignition. What brand of plugs, wires, cap and rotor did you use? Please don't tell me Duralast

[85mustangGT]

I dont remember what brand the parts where but I am sure that I bought them at my local Oreilly Auto Parts so I would guess they would be Master Pro parts.
Guess I should do another tune up this weekend with AC parts?

Nice write up old_master

[old_master]

What year is your Bravada?

[85mustangGT]

1999

[old_master]

Plugs should be AC Delco 41-993 with a gap of .060 If that's what you have in there, and there's less than 100,000 miles on them, they should be good. Cap and rotor... very important, don't cheap out on them, use AC Delco and put a dab of silicone dielectric grease on each terminal, inside and out, of the cap, and a dab on the rotor tip and center. As for wires, AC Delco are good, but way too expensive. Autolite Professional Series wires have better specs and are about 1/3 the price.

Your fuel pressure at 60psi is at the bottom of the spec tolerance, but it's acceptable provided it doesn't go any lower. If it goes below 60psi, it will require some diagnostics to figure out if it's the pump or the regulator. Leakdown at 60psi is almost unbelievable, better check it again, with a cold engine It's possible that the check valve is intermittent in the pump, causing intermittent leakdown. The only way to pinpoint that is with a fuel pressure tester on it when it acts up.

[85mustangGT]

It sat all weekend and this morning I didnt think it was going to start, I cranked it off/on for about 4 minutes and it would not start. Tried the key on/off to prime it, would not start. Gave it a shot of some starting fluid and it fired right up and ran perfect.

Sounds like the fuel pump to me - what do you think?

Replace it with a Delphi part and not the off brand?

[old_master]

Really ought to check max pump output and make sure there is battery voltage and ground at the pump. Maximum output should be approx 108psi. If all of that checks ok, yes, AC Delco pump or Delphi. Don't waste your time, money or sanity on anything else, unless of course, you don't mind changing the pump multiple times.