NO START good fuel, good spark, good ignition, good grounds

[hack6500]

long story, but i need help, and its cruch time...

I got a 2001 Olds Bravada 4.3L 148k. this truck has sat in my driveway all summer while i did the following preparing for this winter...

Things done at 148k:
1) converted CSFI to MPFI using the new fuel injection upgrade kit. (I also got all new upper plenum seals and the proper bracket for this new unit.)
2) new battery & verified all wiring and grounds, cleaned and greased.
3) new alternator (lifetime warranty)
4) new starter (lifetime warranty)
5) new heater core, radiator, water pump etc. (original problem area)
6) new fuel filter

By this point the engine was turning over fine, it started very easily, one try of the starter... AWESOME! PROBLEM SOLVED! .... SO I THOUGHT! then this past weekend I did all the brakes (including all new flanges and emergency brake gear in the rear end, NOT FUN). After bleeding the brakes I drove it around the driveway only, and went away for three days. I get in it yesterday and it wont start, in fact it is acting like it did at about 120k, the first time it did the NO START dance.

Back at 120k I had this exact problem, NO START. I checked my fuel pressure and it was good, but I still threw some parts at it, new plugs, wires, rotor, coil, and ignition module (it had 120k so why not). After those parts and about 4-5 battery drain/charges it started... but it was HARD... After this fiasco the engine started ok, but not every try, and nothing like it did new! This prompted me to replace the CSFI with the new MPFI kit which addressed the exact issue which I appeared to have... HARD START

Other related things that are fairly new:
1) fuel pump & send unit ~110k
2) new spark plugs, rotor, and wires at 120k (after my last no start)

Fast forward to todays NO START and all my repairs, and it sounds the very same. SO FAR... I checked my fuel pressue and its at 61psi and falls to about 56-58 while cranking. I checked my ignition wires and coil and all test good. I am getting good spark at each plug, verified with a well gaped spark tester. The gas tank is 3/4 full with new gas from 3weeks ago, it idled off the 1/4tank in the past 3 weeks in the driveway just fine, until this issue. Fuel cap is a new Stant locking cap just FYI, and has worked fine since 100k mark.

I am currently on my 7th battery drain/charge attempt and its slowly starting to come around, its getting closer to starting every try... but i am putting extra wear on my new battery and starter. I have verified my ignition wiring and proper 12v with no grounds and that all looks good. My fuel pump sounds fully opperational, as well as my starter. I am begining to get a lot of backfiring after releasing the starter, but it hasn't come around to kicking the engine into running.

The Fuel Pressure Regulator included on my MPFI assembly could be the culprit, but that assembly is new (purchased from gmpartsdirect.com) and didn't require any adjustments. Could this regulator have gone bad in the time I have been running this engine (apporimately 3/8 of a tank of gas at idle in the driveway)? Could letting the engine idle so much caused this regulator to fail prematurely? I would rather not tear the top end open to find the fuel injectors, rails and regulator to be fine.

It wants to start, I can tell, and I forsee that it will. But what caused this issue, and when will it decide to do the NO START dance again? I want to figure this thing out so that it doesn't bite me some cold day in January.

THANKS FOR YOUR TIME!
hack6500

[1993blazerlt]

are you getting a fuel injector plus signal? try spraying some gas down the throttle body will this make it kick over?

[Hammer Head]

Are you sure you're not off a tooth on the distributor? It'll be tough to start, run like poo poo & will drain the battery & make you have to jump/ charge it again. Just my thought.

[hack6500]

wow thanks for the quick replys guys...

i just got back from a ride, i got the dang thing going, but it was NOT easy!

i took off the air intake hat and sprayed some starting fluid into the trottle body, it started to make a difference... it actually backfired a couple times and a nice big ole flame shot out of the throttle body (maybe too much ether). it flamed up three times during the dozen or so starting attempts then it finally kicked over... gased it up to 2200rpm and warmed it up, then let it idle itself down to 670rpm.

no more flames.. turned the engine off, and replaced the intake hat. got back in and BOOM the engine started on the FIRST TRY, NO BS. i took it out for a 30mi ride, and no issues. i turned off the engine 3 times for 5min each and it started back up no problems. brought it home and dumped the oil and replaced it while it was hot with some mobil1.

it is now starting and running as good as it did the day i replaced the CSFI with the MPFI. however i still believe there is some problem which i have not corrected with any of my repairs. could it be a bad distributor, or a bad tooth like suggested? even though i got through the NO START dance, and all appears to be fine now?

i intend to get to the bottom of this bs, and i will keep giving updates, thanks again everyone for your time.

hack6500

[Sparky2263]

I'll list a few things to ck. for. First off, strong spark is indicated by pulling the coil wire off. That coil will arc the 1.5" from the coil tower to the coil body if it's good. Big ol' blue spark. The crank sensor gets it sparking so that eliminates that. Second, the distributor prescribes injector timing. Is it correctly indexed? If not, hard starting will continue to be a problem.

Other causes;
Moisture in the distributor cap
Bosch spark plugs
Stuck open t-stat resulting in engine never warming up (causes fuel fouled plugs)
Bad cam sensor (in the dist., should set code)

[Texashorsepower]

I had a bad ignition switch that gave me very similar problems in my 97' Blazer..... Just another thing to consider :D

[Maximus]

I went through 3 ignition switches on my truck.Of course totally different engine but when mine went they went truck would just die right there on the spot.I finally replaced the ****ty Autozone replacements with a good AC Delco switch and never had another problem.But again different engine.

[hack6500]

UPDATE : GOOD NEWS!!

ok so i have been driving the bravada for the past few weeks, and friday it passed NYS Emissions, a glorious day! i have been busy, replaced my transfer case, shocks, and new u-joints (btw the front u needs to be from a trailblazer/2002bravada as the s10 size was wrong) and... oh yes some custom evap hoses!!

i still have a problem, cold starts the engine knocks moderately at 800RPM when throttle is increased say 1400RPM it goes away, then the first 15min running it knocks at idle. i am going to replace these plugs (havent pulled them yet), and likely cap rotor and wires. 3 questions:

1) What will my spark gap be for this 2001 4.3L V6 vinW CSFI engine WHICH HAS BEEN CONVERTED TO MPFI using the new update?

2) Currently i have some auto-lite's but have heard the AC/Delco 45RTS is a good cold weather plug, what is your favorite COLD weather spark plug?

3) Can you suggest any other cold weather igition part upgrades?

As for the ignition, i have checked the ignition signals many times and haven't experienced any disruption of proper voltage at any time. i have tapped this wire a couple places, and made double, triple sure that my modifications were flawless...

[Hammer Head]

I've always gone with between .035 - .040 for gap (that's just me).

I don't really have a favorite cold weather plug.. so long as they work I don't complain, but I am a little biased to AC/Delco though & I like their Rapidfire plugs.

[hack6500]

Well i droped some more damn money into this POS (don't tell it i called it that) but i think it needed to happen.

i bought 6 DENSO Iridium IT16 plugs from auto-zone for 12.99@ which sounds like a friggin rip-off, but i paid happily. i also picked up a new cap-n-rotor with brass contacts, it sure is a lot heavier than the other 2 brands they had, but we will see. i am going to get another set of wires as well, any suggestions here?

the DENSO site says gap these at 0.050 so i think i will do what they state rather than .035-.040 but thanks for that rule of thumb. i hope to restore some gas mileage with these damn things, so that might help pay for them...

[T Man]

I would gap between .055 and .060

[hack6500]

well i got an update, and it just keeps getting better! (really, i think my truck is running the best it has in years!)

well those Denso plugs were very expen$ive at 12.99 a piece, iridium is cool and all but i was not that satisified with them, as compared to ACDelco platinums at 5.99 each. What i did was buy a set of Denso's and a set of ACDelco's and tested them...

i also bought a new set of wires and a cap and rotor (all of these were replaced less than 8k miles ago so i got these just in case). i inspected the cap and rotor to the new parts, and they looked the same... RETURNED! i also inspected each wire, and it looked very very good... RETURNED!

i pulled my AutoLite plugs and sure enough they were garbage, put in the Denso's (gaped at .05) and drove the truck for 2 days, it sounded good, ran good in the cold and performed well. i pulled them and threw in the ACDelco's (gaped at .055) and they preformed just as good as the Denso's IMHO. i returned the Denso's and simply stated 'i wasn't satisfied!'

Both sets of new plugs did help a great deal at cold start, however both sets produced a ticking noise that is only audible when i get on the trottle. it sounds like its coming from the driver side, and i inspected all my plugs and wires but no change... any thoughts?

the truck is running better than ever, passed inspection last Friday, and NO DASH WARNING LIGHTS!! YA!!

hack6500

[1993blazerlt]

well i got an update, and it just keeps getting better! (really, i think my truck is running the best it has in years!)

well those Denso plugs were very expen$ive at 12.99 a piece, iridium is cool and all but i was not that satisified with them, as compared to ACDelco platinums at 5.99 each. What i did was buy a set of Denso's and a set of ACDelco's and tested them...

i also bought a new set of wires and a cap and rotor (all of these were replaced less than 8k miles ago so i got these just in case). i inspected the cap and rotor to the new parts, and they looked the same... RETURNED! i also inspected each wire, and it looked very very good... RETURNED!

i pulled my AutoLite plugs and sure enough they were garbage, put in the Denso's (gaped at .05) and drove the truck for 2 days, it sounded good, ran good in the cold and performed well. i pulled them and threw in the ACDelco's (gaped at .055) and they preformed just as good as the Denso's IMHO. i returned the Denso's and simply stated 'i wasn't satisfied!'

Both sets of new plugs did help a great deal at cold start, however both sets produced a ticking noise that is only audible when i get on the trottle. it sounds like its coming from the driver side, and i inspected all my plugs and wires but no change... any thoughts?

the truck is running better than ever, passed inspection last Friday, and NO DASH WARNING LIGHTS!! YA!!

hack6500

the ticking could be a small exaust leak

[hack6500]

Update @ 158k 10k miles later.

The truck is still running good, and only a few minor issues.
1) the ticking sound is in fact a small exhast leak in the manifold, its right at the secondary air injection inlet. oh well, i can live with it.
2) small coolant leak somewhere, i have had to fill the overflow bottle once... it seems to have been a small leak.
3) car starter + tachless + cold == bad. i am having trouble finding a tach signal, its the WHITE WIRE off the coil right? this is a minor issue, and is only a problem infrequently.
4) by far the best investment was programming the ECU to discriminate against the dumb secondary air system, with this removed I have been very happy.

i do have an issue with my ABS, one day out of nowhere the ABS and eBrake light came on, then went off. This continued until the ABS was staying on more than it was off, the eBrake light is very infrequent. Currently it will turn off only say once a week under different conditions, and when it is off i have verified that the ABS works (didn't test above 30mph). so i threw a abs scanner on it (SnapOn that has worked fine on my vehicle before) and it will not detect any ABS module. climbed under the passenger side, and found a large chunk of ice, kicked it off, wondering where the wiring for the rear ABS sensor is, and anyone thoughts on this. The interior ABS fuse was not broke but has been replaced.

[Mikz86TA]

So whats up with the issue of having Bosch Spark Plugs? CuriousI'll list a few things to ck. for. First off, strong spark is indicated by pulling the coil wire off. That coil will arc the 1.5" from the coil tower to the coil body if it's good. Big ol' blue spark. The crank sensor gets it sparking so that eliminates that. Second, the distributor prescribes injector timing. Is it correctly indexed? If not, hard starting will continue to be a problem.

Other causes;
Moisture in the distributor cap
Bosch spark plugs
Stuck open t-stat resulting in engine never warming up (causes fuel fouled plugs)
Bad cam sensor (in the dist., should set code)

[Mikz86TA]

FYI the Tach is best gotten at the PCM (computer under the hood). It is a white wire on the 4.3 and test only with a meter on AC current setting. The PCM will have a harness with the color red and is a 32pin harness. The white wire in pin #20 is your TACH. PCM is located on the passenger wheelwell with plugs facing firewall--you probably know this already though. Hope this helps :) Update @ 158k 10k miles later.

The truck is still running good, and only a few minor issues.
1) the ticking sound is in fact a small exhast leak in the manifold, its right at the secondary air injection inlet. oh well, i can live with it.
2) small coolant leak somewhere, i have had to fill the overflow bottle once... it seems to have been a small leak.
3) car starter + tachless + cold == bad. i am having trouble finding a tach signal, its the WHITE WIRE off the coil right? this is a minor issue, and is only a problem infrequently.
4) by far the best investment was programming the ECU to discriminate against the dumb secondary air system, with this removed I have been very happy.

i do have an issue with my ABS, one day out of nowhere the ABS and eBrake light came on, then went off. This continued until the ABS was staying on more than it was off, the eBrake light is very infrequent. Currently it will turn off only say once a week under different conditions, and when it is off i have verified that the ABS works (didn't test above 30mph). so i threw a abs scanner on it (SnapOn that has worked fine on my vehicle before) and it will not detect any ABS module. climbed under the passenger side, and found a large chunk of ice, kicked it off, wondering where the wiring for the rear ABS sensor is, and anyone thoughts on this. The interior ABS fuse was not broke but has been replaced.

[20Blazer00]

So whats up with the issue of having Bosch Spark Plugs? Curious

Most of the problems are with the Bosch Multi-tip plugs like the +2 +4 etc. Might be that the electronic resistance values for these plugs throws off the ICM and spark timing. Even though electricity follows the path of least resistance, the other tips offer more resistance than the parts can handle. I don't believe this is a problem with the single tip platinum plugs. I have a set in my 99 Grand Am and they work fine for me...

[Mikz86TA]

OIC--I had gotten a set of +2 Boschs a while back and put them in around 8mos ago. Well except fot the LSide center one--hehe. I got that one in a month back. I havent seen any issues to seak of. I usually dont go for that kind of gimmik and not sure what the heck I was thinkin. I would just do a regular set next time anyway.Most of the problems are with the Bosch Multi-tip plugs like the +2 +4 etc. Might be that the electronic resistance values for these plugs throws off the ICM and spark timing. Even though electricity follows the path of least resistance, the other tips offer more resistance than the parts can handle. I don't believe this is a problem with the single tip platinum plugs. I have a set in my 99 Grand Am and they work fine for me...

[Slacker1357]

I have no idea if your start problem was fixed (too lazy to read through the 20 other replies) but I know my truck didnt start the other day, I checked the fuses and many other things. but my guess was moisture was a problem, and I just kept keying the engine until like 4-5 mins later it turned over (nearly flooded the damn thing)