2004 GMC Savana shuts off at 75mph


#1

Was driving vehicle on highway at 75mph (speed limit) and the engine cut off. Just prior to this event, the vehicle was acting sluggish when stepping on the gas pedal. It took the vehicle from 5-10 seconds to respond to the acceleration requests.

Up until this point, the vehicle would work normally except for the transmission, (we’ve always had a problem with this from day 1), the GMC mechanics said they even took the trany apart and put it back together and couldn’t find any issues. The transmission, when moving from a stopped position will not engage into gear for several seconds (4s - 7s) and when it does, the van pops into gear, jerking the van.

Vehicle: 2004 GMC Savana 1500 passenger Van
Mileage: 105,000
History: has had regular oil changes/tuneups
Primary Issue: Engine shut off while driving at 75mph
Secondary Issue: Trany pops into gear after delay from stopped position (from park to drive or park to reverse)


#2

The go-to answer for a GM vehicle shutting off like that is the crankshaft position sensor. I’d have it replaced (if you haven’t recently) just to take it out of the picture and go from there.


#3

An ignition switch problem could cause an unexpected shut-off too. The symptoms however aren’t especially consistent with that. But worth considering.

When my truck’s auto tran developed that symptom, it was very soon in for a rebuild. You need a transmission specialist to assess the problem. Despite what you were told, taking up to 7 second to engage definitely is an “issue”.


#4

Has anyone checked the ECU for stored fault codes?


#5

Thank you for your suggestions! We have an appointment for an ECU reading this Friday. Wouldn’t the ECU pick up the crankshaft position sensor or ignition switch as a problem if it was intermittently bad? We’re also speculating these possibilities: fuel pump, fuel filter, fuel relay or maybe the Hall Effect Sensor in the distributor. We live in a very rural area, so resources are sparse.


#6

“Wouldn’t the ECU pick up the crankshaft position sensor or ignition switch as a problem if it was intermittently bad?”

Answer: No.


#7

The ignition switch might not, the CPS might as one of the below. You have nothing to lose by checking.

P0335 Crankshaft Position Sensor A Circuit Malfunction
P0336 Crankshaft Position Sensor A Circuit Range/Performance
P0337 Crankshaft Position Sensor A Circuit Low Input
P0338 Crankshaft Position Sensor A Circuit High Input
P0339 Crankshaft Position Sensor A Circuit Intermittent
P0385 Crankshaft Position Sensor B Circuit Malfunction
P0386 Crankshaft Position Sensor B Circuit Range/Performance
P0387 Crankshaft Position Sensor B Circuit Low Input
P0388 Crankshaft Position Sensor B Circuit High Input
P0389 Crankshaft Position Sensor B Circuit Intermittent


#8

Here’s an idea in the meantime to try. Remove the key from the key-ring and only insert the key, nothing else hanging from it. The weight of the other stuff on the key ring swinging as the car goes over bumps may be a contributing factor. If the problem stops, then you’ll have a good clue as to the cause.


#9

Thank you all.

We had the ECU (OBD) reading performed earlier today. There were no fault codes. The mechanic physically checked the CPS and he said it looked good. He also said the fuel was at the proper pressure/rates, he mumbled 60 something…not sure if psi? His thoughts were the fuel pump might be on its way out, but until a code pops, he suggest waiting to spend $900 to replace it. I remember when fuel pumps were put in the engine compartment, easy to get to and replace. Why would a manufacture put it and the fuel filter into a module into the gas tank? I think > 75% of that quote is removing and putting back the fuel tank. How easy would it be to do this yourself? I have most standard tools. This is assuming the pump/filter is the issue. The ignition switch sensor is less likely the cause as the engine died on a very smooth traveling highway, but at this point, anything could be the culprit.


#10

update: there was also a noise associated with the accelerating sluggishness that lead to the engine cutting out. The noise sounded like a faint jet engine trying to lift off the ground, the radio could drown the noise out. The noise was kind of like a low dog growl that escalates (deep rumble to higher pitch noise). You could also feel it, like a small low tremble. The car was trying to go and it couldn’t. Then it was like someone kicked it in the rear and finally the vehicle would accelerate as expected.


#11

Re: Fuel pumps in the gas tank

When the manufacturers switched to modern fuel injection in the late 70’s, early 80’s, they put the fuel pump either in the tank or next to the tank, at the tank’s outlet. The reason is fuel injection requires higher fuel pressures, and it easier to push the fuel rather than pull it. An engine mounted tank has to pull the fuel. Works ok for carbs as carbs don’t need high fuel pressure, but for fuel injection, not so much.

Why does it cost so much to replace the fuel pump? Well, part of it is just the cost of the replacement pump. You could surf to rockauto’s web site and see what replacement fuel pumps cost for your vehicle. There will probably be aftermarket and oem versions available. I expect the shop is quoting the oem version. Then the rest of the cost is labor, which varies greatly depending on how much time is needed to get to the pump.

My old late 70’s VW Rabbit had the pump next to the tank, in the rear wheel well area, so it was easy to access. No fuel tank involvement at all. I think most Toyota sedans have the pump in the tank, but on many of them it is fairly easy to access and remove just by removing the rear seat. i.e. You don’t have to remove the tank to replace the fuel pump. GMC’s, not sure, but it sounds from what you say the tank has to be removed, and would in part explain the high cost to replace the pump.

Removing the tank, that’s not something the typical “change the oil and spark plugs” DIY’er would usually do themselves. I’ve done a variety of DIY repairs to my vehicles, but I’ve never removed a gas tank. Gas tank removal and installation can be very dangerous if the proper procedures and safety aren’t followed. I’d leave that to an expert. It isn’t necessary to use a dealer shop though, any good inde shop can do it.

I concur w/your shop, I wouldn’t be inclined to replace the fuel pump unless there was clear evidence it is the cause of the problem. When I’ve wanted to rule out a fuel pump as a possible problem cause in my vehicles, I’ve rigged up a fuel pressure gauge so that I can watch it while I drive the car. If the fuel pressure drops unexpectedly when it shouldn’t, that’s a big clue there may be something wrong with the fuel pump. It would at least narrow it down to a fuel problem of some sort. Best of luck.


#12

the jet sound sounds like a vacuum leak


#13

Quote: “The noise was kind of like a low dog growl that escalates (deep rumble to higher pitch noise). You could also feel it, like a small low tremble. The car was trying to go and it couldn’t. Then it was like someone kicked it in the rear and finally the vehicle would accelerate as expected.”

Sounds like the transmission slipping to me. And you’ve already said it takes several seconds for the tranny to engage.

The GMC mechanics who “took the tranny apart” probably just dropped the pan and peeked inside. They saw nothing and put the pan back on.