Ok here is the whole story on the new fuel problem.
1987 2.8L MPFI V-6

Over the past 2 wks the car has been taking way too long to start in the morning. Basically I turn the key and hold it for it for a good 10-15secs before it will fire up. (It reminds me of how moms carbed engine acts when its flooded. I have to fight the urge to press the petal down as I'm trying to start it.)

Its worse on warm mornings. If I shut it down after getting it started and start it again it starts fine. After wk aprox 8-9 hours later the car still starts normal. If I let it sit and start it before I go to bed it will start normal. Then Approx 8-9 hours later I got to work it starts fine.

Now if I come home after wk and let it sit from then all night appro 12-15 hrs, it will be hard to start again. Something similar happened 3 years ago and I had 3 cracked injecters that were leaking down overnight. I have a lifetime warrenty on the injecters and labor, but I want to be sure before I take it in. If I go to the dealer and they break it down and the injecters are fine, now I have to pay for the wk. I want to be 100% sure they are bad before I go in.

Yesterday it coded: 45. Engine running rich. We checked what the manuel said. Possible o2, bad injecters, bad fuel pressure regulater. O2 senser is only a few month old. For injecter leaks: Smell the oil for a fuel smell. The dipstick does smell of a hint of gas. So its possible the injecters are bad.

On to how it runs. It has no power (20.81 in the 1/4). 6 mo ago it ran 19.81 with a bad EGR. In those 6mo, we fixed the exhaust leak it had, the EGR code, gave it a major tune up, and even an MSD coil. It should have satayed the same or improved. But the lack of power could also be related to a backfire I have been chasing for a year with no luck. Wehave changed or checked everything to this point, but the fuel sys.

Fuel is the only thing I have not completely tackled. The fuel pump is new as is the fuel filter. Lately, as the car runs I have noticed it seems to skip every now and then. Or it will bog down like when you turn too fast when the tank is low, but the tank was full. At times I am getting a faint gas smell in the cabin. All this is very intermitant. We have checked the fuel pressure at idle and have reved it and its got good pressure (40).

Could it be the regulator? I have heard when it goes, it goes all at once. You will run barley and run way rich. Mileage takes a dump. Is this always the case? Can it happen slowly? If its bad could it cause fuel to get in the oil?

Thanks for your help. I know I wrote alot. I just hoped saying everything might help diagnose the prob.

We may just change the fuel pressure reg. since it is original with 140,000 miles and the cold start injecter also original and see if it helps before we go to the dealer. Illiminate all variables.

 

It's the injectors. My red 85 was sputtering and backfiring and had a hell of a time starting and once it was on the road it would still be sluggish. I had a new fuel pump, filter and pressure read good. Checked the O2, mass air flow, timing, and a ton of other stuff. Finally sent it to a good shop and they found there were 4 clogged injectors. I picked it up last night and this thing runs like a new car. It feels like I could hit low 16's but on a stock motor I know that's a pipe dream:lala: . I have 141,000 on my motor too and highly doubt that the cam lobes are worn down that bad. TomP's may be at 230,000 but not at 140,000 (just kidding Tom!). Another good idea would be to have the old ones sent to Steve @ cruizin performance.com to clean and balance the old set. That's what I'm gonna do after I get some $$$

 

Thanks. I had not thought about clogged injectors causing the backfire. Would clogged injectors explain the starting good when it sits for less than 9 hours, but starting poorly after sitting for 12-15 hrs? This pattern of when it will and won't start well is consitant.

Three years ago, when I had three cracked injectors. The mechanic said based on the symptoms he agreed with it being fuel. When the car sat overnight the fuel would drain out the cracks and in order to start in the morning the fuel had to come all the way from the tank before there was fuel to start the car. He explained it would be worse when its warm because the car primes itself in the cold by sending more fuel quicker.

He said there could be 2 possibilities:
This problem could be explained by the regulater allowing fuel to drain back down the line (not holding vacuum). If injectors, one or more injector may be cracked. These 2 were the only thing that could explain the intermitant starting prob. Both would need time for a small crack or hole to allow all the fuel to drain out.

As before, I want to blame the reg because the injectors are reatively new. How could they be blocked or cracked so quickly? But I keep being told that with a regulater its all or nothing when it goes.

 

Well I'm not too sure about the regulator. the shop was going to charge me $100 parts and labor for each injector. Being on a budget I went home and pulled the rail off of my 86's motor (bottom end is shot , new motor going in soon). I knew the fuel system was good in that car because it never stumbled otr missed a beat except for a hellacious rod knock(s). They just took the old rail/injectors off and put the new (other) rail/injectors on so they didn't mess with the regulator. In terms of the time frame between starts-- yes. Mine would take a while to start but once it did it would start up alot easier. Is there a possibility that the three that were not previously cracked were never replaced? Maybe the remaining ones have kicked the bucket (unless you changed all 6 before)

 

A fuel pressure gauge can diagnose the regulator. You should buy/rent/borrow one in order to test the system.

Do you just flip the key from "off" to "crank"? If so, you're not letting the pump prime enough. You need to put the key from "off" to "on/test lights"- where all the dash lights come on, and you can turn on your radio, roll the windows down, etc... the key position right before "crank". Youll hear the pump hum for a few seconds, and then stop. Now move the key from "on" to "crank".

If I jump the key from off to crank, my car cranks forever. If I let the system prime first, it'll start with in 1/2-3/4 seconds. Oddly enough, it was a slightly faster start before I put the MSD 6AL box in.

Oh- as to the code 45, you said the oxygen sensor is relatively new. Make sure the oxy sensor wire hasn't moved, and didn't melt itself on the exhaust pipe. This will ground the oxy sensor, and if this happens, the computer will read the sensor as "zero voltage", and turn on code 45.

 

No I paid for all new ones and made sure to get all my old ones back. So I have the original 6. Now onless the guy pulled a fast one...But none the less if I'm positive its the injectors they dealer will replace them for free: injectors and labor. I just have to sure before I give them the car. It don't want them to find out its something else and charge me out the yag for work I could now do myself. I would replace the injectors myself, but I paid for GM parts so I could have that warrenty and I'm gonna make them do it. Heck I may get some off a yard car and try it if it fixes it, then I can put the old ones back in and make them replace them. Its just a lot of trouble to go thru.

 

Oops, you said you do have a gauge. Car off, crimp the return hose shut with a pair of hose crimpers (or vise grips with the tips wrapped in a towel so you don't cut the hose). Turn the key to "on" but don't start the car- with the return line blocked, the fuel pump will reach dead head pressure (aka max), and you should see 60 PSI. I'll look up the procedure for testing the regulator when I get home to my manual. You can also pull the vacuum line from the regulator- if there's fuel in the vac line, the regulator's shot.

If it's shot, consider replacing the regulator with an aftermarket adjustable one, or do the "make your own AFPR" tech article from thirdgen.org's tech section.

You also said you checked pressure at idle. What is the primed pressure? That's found by turning the key from "off" to "on/test lights", and watching the gauge. Don't start the car, and don't have any fuel lines pinched shut.

 

The code 45 went away today, so the O2 is not grounded.

I have always started the car from off to crank. The few times I did prime the sys. Before I cranked it, it did start faster. Normally w/o priming the car starts in a sec or 2 worse case. We did check it and it is priming properly. I have not waited overnight, primed and then started though. I will try this tomorrow. We are going to check the car some more tonight with the gauge.

 

Even some V8 TPI guys do that, and wonder why their car takes forever to start, so you're not alone. GM should have mentioned it in the owner's manual or something!

And you know this for a fact? Wires bounce around. I'm not saying you're wrong, but you should at least look at it!