Hard Start in 96 454. Please Help, this is a doozy

[orphan40]

I've been researching hard starts and I found my problem, so I figured I'd just throw this out there... Did you check your distributor gear? My truck gradually got harder to start over a few days then finally quit starting all together. I changed the cap and it started, but it stumbled and wasn't starting like it used to. So I pulled the dist and found this. The top is the new dist gear.

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[brycebba]

I haven't checked that. Would that make it hard to start all the time or just hot? My truck only has 65k, it wouldn't have crazy wear that soon would it

- Bryce -

 

[orphan40]

Mine started reliably until last week. Got harder and harder to start, then nothing. No telling how long the gear has been like this, but I've got 178k on mine and know nothing of it's mechanical history before my ownership. It just raised my suspicions because out of that laundry list of new parts and tests run, it mentions nothing of the distributor itself. Like I said, I'm just throwing it out there. It may be worth a shot.

 

[brycebba]

If I end up pulling the plenum off this week I will read up on how to check that part out

- Bryce -

 

[brycebba]

Alright, I drove about 30 miles on the stock tune and it was not running well at all. Sputtering kind of like a miss or dead cylinder. Pulled the plug that I pulled last night and to me it seems a little lighter than last night on the performance tune. The lighting made the performance tune look darker than it really was.

Performance tune

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Stock tune

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So what would make a stock tune starve for fuel more than a performance tune? This makes no sense to me. Checked my fuel pressure again and if you cycle the key it primes to about 55 and settles still at 48 when running. I'm lost

- Bryce -

 

[88GMCtruck]

I'm wondering if it's getting a bad reading somewhere like the o2 sensors? That was my next guess on mine.

 

[brycebba]

I did some data logging using my flashpaq and the 02 sensors seem to be moving all around but I guess within the normal range

- Bryce -

 

[98_k1500]

Well that last post to test unplugging it didnt change anything. Not sure what that means

Something has got to be up here. Somehow it has to be restricting the fuel. Mine will not start and will foul the plugs on my 4.3 with it unplugged. I would assume it should do the same on the 454...

 

[JollyGreen]

Could be the O2 sensors. If it's thinking there's too much fuel it'll tell the computer to start cutting back. Those plugs appear awfully white. Other things to check might be the crankshaft sensor, and as mentioned, the distributor gear.

It seems to me that the fuel pressure should be higher than what you're getting. Don't rule out a bad FPR.

 

[brycebba]

I had to replace one of the O2 sensors before the cat a while back so it is under warranty. I suppose I could buy another one and see if they will let me swap out the existing one. I am on my 3rd Fpr designed for the 454 now and they all seem to be that low. I could try a 350 one but I just dread pulling the plenum off again. I don't have any codes currently but what would the plugs look like if my cats were getting worse but not enough to trigger codes yet? Is there even a way to test those?

- Bryce -