Discovery 3.9 Cold Start Problem

[discorunner94]

Hello all:

95 Discovery 3.9 has trouble cold starting. Typically turns over and will grab, gargle a bit, then correct itself and run well. Some days after a heavy rain, it doesn’t start at all. I replaced the coil and cleaned all the connections and it’s started when wet out. Today, beautiful and dry morning - coldest in months, won’t fire up at all. Seem to be getting gas because it will fire a bit, then die. Sometimes caressing the pedal makes it go, but not today. Was just trying to make it to the weekend, because cap/rotor/plugs/wires are coming in the mail for Labor Day tune-up. Car has thrown Code 48, but not since I cleaned the IACV a few months ago. Any ideas? Need this thing dependable going into winter.

Cheers,

 

[Toran]

What do your plugs look like?

 

[Jimmy]

Have you looked under the distributor cap?

 

[jymmiejamz]

I’d be starting with a new cap and rotor. I think the red rotors are supposed to be the best ones available.

how cold is cold?

 

[Blueboy]

For sure the Red Rotors are better than the recent junk being sold under OEM LR brand. Bought mine at RN.
Also recent problems with cap as well.
Powerspark Ignition pretty sure is providing the red rotors. They also have caps.

 

[Jimmy]

The ones I bought at Autozone, and I think were "Made in Italy" under the AC Delco name, have been serving me well for 6-10 years (can't recall when I replaced them; it was long ago). I don't put many miles on it each year, FWIW.

 

[discorunner94]

thanks for all your responses — i did stepper motor (to combat intermittent code 48), cap/rotor, coil, plugs and wires as a pre-winter tune up. vehicle is running much better. one peculiarity: when i fire it up cold, the car bogs a little bit and then corrects its idle after a few seconds. any ideas? on an old 4Runner of mine this happened because of a cold start injector; not sure if discos have one. guess it could be poor contacts to stepper motor, but i’ve cleaned those.
cheers,

 

[ptschram]

Fuel pressure???

 

[DiscoClay]

thanks for all your responses — i did stepper motor (to combat intermittent code 48), cap/rotor, coil, plugs and wires as a pre-winter tune up. vehicle is running much better. one peculiarity: when i fire it up cold, the car bogs a little bit and then corrects its idle after a few seconds. any ideas? on an old 4Runner of mine this happened because of a cold start injector; not sure if discos have one. guess it could be poor contacts to stepper motor, but i’ve cleaned those.
cheers,

Two words: Check Valve

It appears there are circumstances that cause the pressure to drop off in the fuel line when it's not in use

There are several possible reasons but they all seem to greatly impact engine start (cold and hot).

After installing new fuel lines all the way back to the tank...and used AN6 fittings and a screw-on filter, I found the pressure would not hold long in the system when the engine was not actually running. I added an inline fuel check valve between the engine and the fuel pump (near the original filter location).

Often aftermarket "OEM spec" fuel pumps have *POOR* quality check valves and some cheap chinese aftermarket fuel pumps do not even include an integral check valve.

While the initial two second[ish] pump engagement (at ignition switch position 2) helps, it is not much of a substitute for maintaining line pressure in the rails.

 

[discostew]

The ones I bought at Autozone, and I think were "Made in Italy" under the AC Delco name, have been serving me well for 6-10 years (can't recall when I replaced them; it was long ago). I don't put many miles on it each year, FWIW.

That would make sense since it's a Buick engine. Around 2009 I was told there was a bad batch of rotors. A guy names Sweeney said it. Recently I put a cap and rotor in a Defender that only lasted about 5,000 miles. I think if there really was a bad bunch of rotors they made it back into the supply chain.