1999 Blazer 4wd - Starting Issues And Power

dougg01 · May 21, 2009

4.3 auto 4dr 4wd

Just got it.

Previous owner told me that lately it had been hard to start. Didn't mention power loss.

mechanically sound, idles and low, part-throttle is good and smooth. Seems to have some power. In 4wd climing around the field it does fine. This is to be my new DD.

Cleaned IAC, TB, EGR, and ran seafoam through it. Idle is even smoother, but still a hard start. replaced fuel filter with purolator brand.

Tries to start...seems to try to catch and doesn't. Sometimes takes 3-4 tires. A couple times it took some ether to get it going. Repeated attempts does NOT result in a heavy fuel smell. There really isn't much at all. Subsequent restarts w/i a few hours are typically instant.

No codes.

reset computer. no change.

fuel pressure key on - 52psi steady. Book says it's supposed to drop...?

fuel pressure at idle - 52psi steady

fuel pres never drops below 52 psi.

1/4 throttle or more w/o load FP will increase to 60psi. Revs freely to 3k or better with a solid tap of the pedal.

1/4 throttle under load FP will increase to 60psi.

More than 1/4 throttle under load and FP goes to about 55psi and the truck struggles. Approaching 3,000rpm over 1/2 throttle under load and it feels like it hit a brick wall. Weak.

Talked to a buddy who thought though the pump seems to be putting out adequate pressure, that the volume could be low. It is the original pump with nearing 200,000 miles.

What about a cheaper alternative for the fuel pump than what GM, advance and the others offer...? I've put walbro in F-bodies (we currently have two LT1 firebirds) and they work fine but don't know what pressure they are capable of (255gph @ around 45psi on one of them).

I looked all over the place and did NOT see a FP regulator. The lines look in good shape and the pump sounds to spin up just fine. On key OFF it runs again then stops. Pressure is not bleeding off. After the last shutdown the FP was still about 50psi 2 hours later. My firebird can't do that anymore and that was true right after I put in the new pump on that thing.

It could be the FP and very well could be, but I don't want to change it if its not. Money is tight and I need to start driving this thing, but won't till I can pull into traffic without dying and it will start on the first turn of the key.

TIA for any advice......

Draenor · May 21, 2009

Unfortunately, the FPR on a 4.3 is part of whats called the "spider". It is know to give problems. To get to it, the intake manifold need to be removed.

dougg01 · May 21, 2009

Unfortunately, the FPR on a 4.3 is part of whats called the "spider". It is know to give problems. To get to it, the intake manifold need to be removed.

The whole intake or just the upper...?

How do I determine it's the FPR and NOT the pump.

FPR is a LOT cheaper.

Do the originals have a problem with sticking...?

The symptoms would suggest an FPR problem I think.

bill190 · May 21, 2009

The following link has general fuel system service advice. Then a GM factory fuel and emissions service manual for your year/model would have detailed instructions for testing/replacing everything in your fuel system, give the specs for everything, etc. I think my book has around 90 pages on just this! So plenty of detailed information/instructions/troubleshooting.

In addition there is also a general service manual book, an electrical diagrams book, and a unit repair book. You can order a factory service manual set from a GM dealer.

Fuel system service...

http://www.asashop.org/autoinc/june98/techtotech.htm

Draenor · May 21, 2009

Unfortunately, the FPR on a 4.3 is part of whats called the "spider". It is know to give problems. To get to it, the intake manifold need to be removed.

The whole intake or just the upper...? Upper. Its not that bad of a job, but its a pain.

How do I determine it's the FPR and NOT the pump. Thats a difficult one. As pressure seems ok, the volume output could be low. Are you running lean at WOT??

FPR is a LOT cheaper. Its a SFI system, its all one unit. The Spider assembly is not that cheap, about the same if not more than a fuel pump.

Do the originals have a problem with sticking...? Yes the poppets in the injectors can stick.

The symptoms would suggest an FPR problem I think.

VR021302 · May 21, 2009

An old friend of mine used to have a Sonoma with the 4.3 and his had the same problem. The feed line in the intake would leak and had the same symptoms as yours.

We pulled the intake and just replaced the line with some fuel line and never had any more problems.

dougg01 · May 21, 2009

In a bit I'll address each piece of advice seperately, but I'll do a down and dirty first....

GM service manuals....? Seriously...? I could replace the pump, tank, lines, and injectors for what that costs. I have the CDs somewhere, but am not sure they'll run on XP SP3. Not sure my set of CDs (from 2001 I think) cover the S-series stuff or V-6.

Intake coming off a PITB. I work on 4th-gen f-bodies and LT1s at that. Everything is a PITB. Its a way of life. Having played around with my old 94 S-10 quite a bit.....and looking at this one....There really isn't much there. If I'm only taking the upper off, should be cake.

Fuel line leak...? I am not discounting it, but there is no fuel smell after prolonged and repeated cranking. If it's bleeding somewhere I'd expect to smell something. Might not, but I think I should.

That upper use an o-ring gasket or just a rubber sandwich...?

Oh......Advance sells the FPR for $46 so it IS seperate....somehow.

Web tech sources on this stuff are HARD to find. If I want to remove a TB cover screw on a F-body I can find 20 tech articles telling me how to do it 5 different ways. Either the f-body crowd is exceptionally stupid and needs this kind of guidance OR they are a lot more willing to share information.

VR021302 · May 21, 2009

Ironically the Sonoma never smelled of fuel, I guess cause it leaked into the intake. Once it started it ran decent though.

dougg01 · May 21, 2009

Ironically the Sonoma never smelled of fuel, I guess cause it leaked into the intake. Once it started it ran decent though.

Well, that would suck. I want a sign....blinking...in NEON....telling me 'LOOK HERE, can't you smell the fuel.?!'

So....I got a 'could be a line' and a 'could be a FPR' and no one so far is blaming the pump.

I read the asa article. Good read. Is there a screen on the FPR on these...? My experience with TBI and my MPFI on the LT1 tells me no, but I could be wrong.

Do the injectors on these CMFI (or whatever they call it) in 1999 have the screen on the injectors...? The TBI does and I know if they get dirtied up it can cause this condition. Runs decent, but down on power from mid-range up and hard start.

bill190 · May 22, 2009

GM service manuals....? Seriously...?

Note you are asking your questions in the "Ask the GM Technician" area!

So yes quite serious!

I feel the BEST source of information is straight from the horse’s mouth as they say! (Manufacturer in this case.)

Although I don't work for GM or any GM dealer, I have done factory repair work most of my life for various companies. I and everybody else I know who does repair work "the right way" always has factory service manuals handy. And we frequently use them. Not always, but sometimes you can't do much without them.

Actually there is a whole world of factory printed service manuals and publications out there for just about any product which can be repaired. Few people seem to know about this except the repair people. But usually these are available to the public. Just ask the manufacturer or distributor of the product.

dougg01 · May 22, 2009

GM service manuals....? Seriously...?

Note you are asking your questions in the "Ask the GM Technician" area!

So yes quite serious!

I feel the BEST source of information is straight from the horse's mouth as they say! (Manufacturer in this case.)

Although I don't work for GM or any GM dealer, I have done factory repair work most of my life for various companies. I and everybody else I know who does repair work "the right way" always has factory service manuals handy. And we frequently use them. Not always, but sometimes you can't do much without them.

Actually there is a whole world of factory printed service manuals and publications out there for just about any product which can be repaired. Few people seem to know about this except the repair people. But usually these are available to the public. Just ask the manufacturer or distributor of the product.

I hear what you are saying, BUT......

The cost of the bundle make little sense when I could use virtually the same amount of money to replace the fuel system.....

Admittedly I don't know everything there is to know about GM EFI and tuning, but I do know folks good at programming them and I know enough to do the work without being totally dangerous. I am trying to diagnose a problem without spending all the $$$$ in the world. The book bundle and repairs will bust any budget I do or do not have.

And.....factory service manuals are not well updates (or any repair manual). R&R on the Opti on my car is supposed to be 8hrs for a trained employee. If it takes me more than 2 hours (that is if I'm not doing something else at the same time) there is something wrong. I can swap tranny in under 90 minutes without a lift or tranny jack. Repetition breeds efficiency.

Point is.....putting knowledge to practice is what makes you good at what you do. I am only fair on some things. A GM tech came over once and we decided to change my plugs and he had 5 done before I could complete 2 and I have 1 3/4 headers on there. Can you tell I don't like to change my plugs...? I'd rather swap the tranny. The books didn't teach him to change my plugs with those headers.....He's just a more adept mechanic than I am. Well, he's a mechanic and I'm a hobbyist. I'd not have fun if I HAD to do it for a living. Tried.....took the fun right out of it.

I'm simply asking the brightest folks how to get from point A to point B here. I'm not dogging too much on the books, but they are not essential to the logevity of my vehicles. I asked for some expert advice and a direction to follow. Last I checked that stuff was still, usually given freely.

Now....I have a tech on another site telling me if the pump makes 60psi then it's good. In my post I clearly stated I have observed at least 60psi.

I'll try to get a FPR and plenum gasket today. Worst case....it's fine and I replace it anyway then buy a walbro 190gph pump and fix it.

Draenor · May 22, 2009

I'll try to get a FPR and plenum gasket today. Worst case....it's fine and I replace it anyway then buy a walbro 190gph pump and fix it.

Let us know how it turns out.

dougg01 · May 26, 2009

Let us know how it turns out.

I didn't get to it until yesterday afternoon and had to stop to fix dinner....but.

It's apart and everything is clean and the FPR has been swapped.

What did I find....besides a LOT of carbon build up...?

Area around port 6 was washed clean. This is directly adjacent to the FPR.

What else did I find....the FPR doesn't us a hose or anything and it gets a LOT of carbon on it and in it. 195,000mi I'd guess it could be worse.

The spider is weird. Why on earth would you go from the port injection to this thing...? To avoid having a fuel rail...? IT's dumb, but some engineers thought it would be an improvement.

Anyway, I need to get another can of TB cleaner on my way home and actually clean the TB because that's all that's left that needs de-gunked. I should have it together this evening and see how she runs.

Next.....the OIL LEAK.... At the line block going to the block adapater. I got gasket and o-rings, but I'm dreading it due to the mess.

Draenor · May 26, 2009

Let us know how it turns out.

I didn't get to it until yesterday afternoon and had to stop to fix dinner....but.

It's apart and everything is clean and the FPR has been swapped.

What did I find....besides a LOT of carbon build up...?

Area around port 6 was washed clean. This is directly adjacent to the FPR.

What else did I find....the FPR doesn't us a hose or anything and it gets a LOT of carbon on it and in it. 195,000mi I'd guess it could be worse.

The spider is weird. Why on earth would you go from the port injection to this thing...? To avoid having a fuel rail...? IT's dumb, but some engineers thought it would be an improvement.

Anyway, I need to get another can of TB cleaner on my way home and actually clean the TB because that's all that's left that needs de-gunked. I should have it together this evening and see how she runs.

Next.....the OIL LEAK.... At the line block going to the block adapater. I got gasket and o-rings, but I'm dreading it due to the mess.

It is a crappy design, and yes it gets very dirty in there.

I see some guys are swaping in the marine upper intakes instead of replacing the spider or FPR. I am going to do that myself if I ever expeirence a problem with it.

dougg01 · May 26, 2009

It is a crappy design, and yes it gets very dirty in there.

I see some guys are swaping in the marine upper intakes instead of replacing the spider or FPR. I am going to do that myself if I ever expeirence a problem with it.

When the parts counter droid said there were a LOT of the FPRs on the shelf.....I'd figured there was something to it. I'm not 100% positive this will fix the issue, but I am leaning that way. There's no other reason for the #6 port to have been so clean when all the others were covered in a nasty cake of carbon. I'd like to hook the fuel lines up and run the pump up one time to check for leaks. Maybe even crank it over to see if the fuel is coming out the poppet valves. More likely....I'll put it all back together and try to run it. With everything CLEAN.......the work will be MUCH easier. You can tell it wasn't owned by a 'car guy'.