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

[brycebba]

I used a Delphi fpr for our 454 and then swapped in a BWD model for the 454. I initially was going to try the 350 model that runs at 4 bar but was advised on here not to because it would be too much fuel for my mods. If it weren't such a pain I would try a 350 model but I don't want to go through that unless there is good reason. When I pulled my plugs before the pump they were kind of on the light side like it's running a little lean. I'm going to pull one of the new ones tonight to see if the color is different.

I tried the paperclip and it started about the same I think. I did get a couple codes after running it for about 20 minutes this way. Low voltage signal for CTS and a circuit issue for the ignition control module and then it started running kind of rough. I replaced the CTS just for fun but it didn't seem to change anything

It used to have to sit for a while to have the hard start after running but it just did it after sitting for 15 minutes.

- Bryce -

 

[454cid]

I don't know if it would cause starting issues or not since timing is handled by the PCM, but the distributors can wear....... both the gears and bearings.

 

[brycebba]

Could be, I'm not sure. I pulled a plug to see how it has been running since the pump and this thing is white! I'm dropping my tuner to stock to drive around for a bit to see if that changes the coloring and the start conditions. Why the freak would they be white!? Unless maybe I really should try the 350 fpr but 24lb injectors running at 4 bar or roughly 60 psi seems like a ton more than stock injectors at 3 bar. Could my flashpaq really go that hard on custom performance tuning that it could actually use all that fuel?

You must be registered for see images

You must be registered for see images

- Bryce -

 

[98_k1500]

Bummer about the CTS. Alot of times that is the issue. I would say you definitely have a lean issue. Maybe the 350 FPR is not such a bad idea. The o2 sensors should be able to compensate. Maybe the factory fuel pressure is just not enough and the pulse width needed to flow enough fuel is outside the parameters of your tune.

 

[brycebba]

So do you think if I drive for a bit on stock tune and the plugs tan up then I should bump to the 350 fpr to try?

- Bryce -

 

[98_k1500]

This may be getting a touch out of my area of expertise with the 454, but it definitely needs some more fuel from somewhere. Either from pulse width or fuel pressure. Not sure if you can get to a piece of the return line where its rubber, but you could kink or clamp it shut and see if the bump in pressure helps the hard start. Would probably be easier to try this than to get to the FPR, and just take a shot in the dark.

 

[brycebba]

Is the fuel return line the one that is next to the line out of the filter? There are two metal lines right there that both go to rubber and seem to lead up to the connections on the fuel rail? If so, that should be easy to clamp

- Bryce -

 

[brycebba]

Put it on the stock tune and ran it to work this morning and it stumbles a fair amount when you put your foot in it when the torque converter is locked and you are less than 3k RPMs. Im pulling a plug again tonight to see how it looks. Im hoping it is black indicating that I need to find some middle ground in the tune because it is now running rich which is causing the stumbles.

***Side note before I get back on topic. I have been thinking about taking my old fuel rail and experimenting with cutting the fpr basket for lack of a better known term and extending it out from behind the plenum and mount it above so that the regulator can be changed without removing the plenum. Im just not sure what I would use to extend it. I know a lot of folks say not to use rubber line at that pressure when it is just clamped on so I guess I would need to find some other way. Anywho, Im just sick of pulling that plenum off.

 

[brycebba]

^^^ paperclip in the plug will make it read hot if you think its overfueling on startup. I had a TBI 4.3 do this to me. Coolant temp sensor was working, but after it sat a while, it would read -40°. Flooded it so bad it was nearly impossible to start. Once it started, it would act right. I ran it around for about a week with it unplugged and a paperclip in the plug to make it not flood while i sorted out other issues. Simple test. If it still will not start, try it with the coolant temp unplugged. If neither helps, I would say the problem is not with the CTS.

I guess this isnt a question of the CTS working, its more about if given a false reading it starts easy based on my new discovery of a lean running condition. If I unplug the CTS will it read -40 and add additional fuel at start up? Based on my plugs showing a lean condition I wonder if when the temp is cold and it fires right up that maybe it is actually just the right amount of fuel and a hot start is actually running lean due to a properly working CTS. I just wonder if I can trick the computer into thinking its cold even when the engine is hot and has sat for a while if it would fire up quickly if given more fuel. Basically is the amount of fuel on a cold start really the amount that a hot start should get. I dont even know if this is a valid test of the fuel system at starting time or not.

 

[brycebba]

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