Series One hard start and sputer under load

[dirkmc3]

I've searched the forum and found lots of information and have some ideas already but have an additional question.

98 Series I disco 154K on the clock. Its a winter and hunting truck so the check engine light has been on for oh...tha last 50K. I started to have issues when hot with sputtering/misfiring under load and it has gotten profressively worse.
It recently would not start so I went through some basics. Batt ok, Spark ok I thought it was getting fuel since I could smell a little. But...some starter fluid in the intake and she fired up and idled just fine. Same issue though sputters terribly when warmed up and under heavy load or heavy throttle. Replaced a tested ok set of Coil packs already and I know there could be other issues.

So...two questions, should I be able to hear the fuel pump prime when I turn the key over?? and if the fuel pressue was bad, would it continue to run after the starter fluid burned off? Was it just enough to begin to "pull fuel"

Also...the warmed up thing...crank position sensor?? is it effected by engine heat?

[Spike555]

Man neglected trucks are so hard to fix, usually a ton of simple problems working together to create one huge problem.
Check the fuel pressure, on the passenger side of the engine is a schrader valve, using a fuel pressure tester (rent one) check the fuel PSI, you need in the mid 30's, any less and it may idle or run at low speed.
As for the hard start when hot it could be as simple as the fuel temp sensor, or the fuel pump and now the fuel pump is so bad its acting up more often.
Knowing why the check engine light is on would help too.

[jake22si]

low octane fuel can also cause these symptoms, the timing gets advanced causing overheating and unburnt fuel through the cats. Change the plugs and use some 93 octane fuel maybe with some additive to get the water out.

[ihscouts]

BS to the low octane. Just to clarify, only need 91 octane to meet the "premium" octane fuel requirement..... 93 is over kill and costs more. Running 83 octane makes little difference, I've run it in mine for some time without issue but what is different is I keep mine in excellent tune. I get maybe a few less miles per tank. Highly doubt overheating, compression ratio aint a sports car nor that finicky about what it gets. You'll get just as much carbon build up with 83 as you will with 91......

dirkmc3 you need to pull the codes to get the right kind of help on here without us coming over to your house. 50k in poor tune it will take some work to get your motor out of the crapper.

[jake22si]

Originally Posted by ihscouts

BS to the low octane. Just to clarify, only need 91 octane to meet the "premium" octane fuel requirement..... 93 is over kill and costs more. Running 83 octane makes little difference, I've run it in mine for some time without issue but what is different is I keep mine in excellent tune. I get maybe a few less miles per tank. Highly doubt overheating, compression ratio aint a sports car nor that finicky about what it gets. You'll get just as much carbon build up with 83 as you will with 91......

dirkmc3 you need to pull the codes to get the right kind of help on here without us coming over to your house. 50k in poor tune it will take some work to get your motor out of the crapper.

Maybe its just mine that doesn't like 87 or 89 octane, or maybe because I have 200k+ miles I don't know. 91 is only available at 1 local gas station and I don't go there often so I just get the 93. I throw 02 sensor codes and misfires when I use the lower octane, and I get bad spark knock, which advances the timing causing things to get hotter than normal when driving any length at highway speeds. Have had zero problems since I switched to the 93, and get 5-6 more mpg than before. So that was what worked for me thats all.

[ihscouts]

If your knocking at highway speed something other than low octane is causing it. Cooling system in good shape, unrestricted? Overheating will cause the knock and the sensors won't overcome it, can't.

[jake22si]

Ok, just saying that the symptoms went away after switching to higher octane fuel. Trust me I don't want to use it, but seems to be the difference for mine. This new gas is not as good as it used to be