1999 sub just quit going down freeway.

I have a 1999 GMC with 280,000 miles. No engine light on. I was going down the freeway and the engine light flashed 5 times and the engine quit. Left 4 ways on and the battery went dead. Towed home. Checked code and it was p0304. Because the battery was dead for a few days I don't know if it's from back then or just now with me trying to start it. The fuel presser is good and it holds presser. The engine try's to start I think. It stumbles and simi locks like it's trying to fire but not enought to keep it turning. fuse's look good, the ones I know of. Any ideas? I am a shade tree guy and don't mind throwing a few parts in it on the guest. Thanks Dave

Need to know what motor. What some folks consider good fuel pressure most of the time isn't, so need to know that also.

I have a 1999 GMC with 280,000 miles. No engine light on. I was going down the freeway and the engine light flashed 5 times and the engine quit. Left 4 ways on and the battery went dead. Towed home. Checked code and it was p0304. Because the battery was dead for a few days I don't know if it's from back then or just now with me trying to start it. The fuel presser is good and it holds presser. The engine try's to start I think. It stumbles and simi locks like it's trying to fire but not enought to keep it turning. fuse's look good, the ones I know of. Any ideas? I am a shade tree guy and don't mind throwing a few parts in it on the guest. Thanks Dave

with a 1999 gmc suburban the fuel pressure need be key on eng off 62-65psi. it may start at a slightly lower pressure like 55psi maybe. p0304 is cyl4 miss fire. low fuel pressure can do that. if this is the only code and you have the pressure tested with a pressure gauge then this maybe a distributor problem/ICM etc.......... on these vehicles the distributors do fail @ 175K miles and higher. check for wobble of the rotor . my guess its the 350CU OBS...

Triple 7 and j cat thanks. I replaced the distributor cap as it had a hole cut thru it via spark. The car started up. I am now replacing the spark plugs. With 280,000 on the 5.7 and I have never changed the plugs, wire, cap or injectors. It's time! Will report back when done. Thanks Guys

Triple 7 and j cat thanks. I replaced the distributor cap as it had a hole cut thru it via spark. The car started up. I am now replacing the spark plugs. With 280,000 on the 5.7 and I have never changed the plugs, wire, cap or injectors. It's time! Will report back when done. Thanks Guys

when you get a new GM truck it won't run this long that good ! maybe 100K if your lucky...

All work done! Plugs came out with cold engine after 280,000 (purchased new) with no problems. Thanks again

All work done! Plugs came out with cold engine after 280,000 (purchased new) with no problems. Thanks again

post a picture of one of the plugs.. what was the plug # ?

post a picture of one of the plugs.. what was the plug # ?

Agreed, would be interesting to see those plugs.

Not to hijack this thread but of the '96-99 Suburbans, is there a preferred year? My 99 was great but had so many electrical gremlins and I heard this may be a common problem with the 99s.

Photos

One at a time I guess.

280,000 mile cap with hole arced into it.

280,000 mile plug.

Photos

the gap looks huge but the burn still looks good.

the engine must run better now with more power ..

usually old plugs/plug wires and cap rotor cause slow cold starts.

It does start faster. This is my back up car so I can get to work! 89,000 miles.

It does start faster. This is my back up car so I can get to work! 89,000 miles.


NICE CADDY.. MPG 7 on that one. good thing gas prices are down to below $2 / gallon... last I checked here its down to $1.80.