Chevy & GMC Vans

Hey folks, new guy here. I've owned my 95 G2500 for a little over a year. It's a love/hate relationship for me. I've been chasing down a stalling issue for almost a year now and I'm not quite sure I've got it figured out still. Someone told me it sounded like it might be a vacuum issue so I'm looking to replace all the vacuum lines but don't have drill bits to size them, they're old enough I can't read any writing on them too. Can anyone tell me what size I would need?

Are the vacuum lines that go from the rear of the intake up to the front for the brake booster and vacuum canister the only lines that are there to replace?

This is the 5.7L engine I have.

Welcome to the forum.
Chop off a half inch piece of the your vacuum line and take it to the store with you

So I've been chasing this problem down since last summer when it first started to happen but still haven't figured it out. I own a 95 G2500 with the 5.7L

Basically if I try driving anywhere when the ambient outside temp is over 70F, the van will randomly stall on me, typically when I let off the accelerator to begin slowing down but it has stalled several times when driving at highway speeds. It seems like the warming the weather, the worse the problem gets and it occurs more frequently when driving and also takes longer to restart. When it does this, the starter seems to crank very slow almost as if the battery is very low but I know it's fine.

So far here's everything I've replaced, I'd say all of this stuff has been purchased in the last 2 or 3 months with a few things being about 6 months old.

- ignition coil
- ignition control module
- cap & rotor
- plugs
- coolant sensor & pigtail
- oxygen sensor
- fuel filter

My next possible options are camshaft position sensor or the fuel pump.

In ways it does seem to be vapor lock but the way it shuts down when driving makes me suspect something else.

One question I do have that might help me lean more towards vapor lock, will the temperature of gasses coming from my muffler be hot enough to create the vapor lock conditions? I just realized today that the muffler sits just before the rear axle and is pretty centered under the van, which so is the fuel tank. I don't have a turn down on the tip, it just exits straight out.

Would also like to know the location of the cam position sensor.

TIA

Please post your questions in the "G Vans" section. This doesn't belong in Astro/Safari. Thanks.
(topic moved)

Just got back home from a very short drive to a local gas station. Left the van running while inside and on the way back to my place I noticed the engine light came on for less than 30 seconds and then went out. Checked the codes as soon as I got back home and code 54 (fuel pump circuit voltage low)this is the first time I've ever had this code but could be the underlying cause to all my problems.

Is this code typically associated with the pump relay or the pump itself?

Relay.
It's a $5 part so change it first.

MountainManJoe wrote: ↑Sun Apr 28, 2024 8:20 am Relay.
It's a $5 part so change it first.

It's like $20 here at O'Reilly's and Car Quest

$5 or $20 doesn't matter if you have to change it every 30 years

MountainManJoe wrote: ↑Sun Apr 28, 2024 8:43 am $5 or $20 doesn't matter if you have to change it every 30 years

Can you tell me the location of it? Not familiar with where the relays are located on these vans. I think there is one mounted somewhere near the washer fluid reservoir and brake booster but I might be wrong

You can find further service information here:
https://charm.li/Chevy%20Truck/1995/G%2 ... Diagnosis/

MountainManJoe wrote: ↑Sun Apr 28, 2024 9:38 am You can find further service information here:
https://charm.li/Chevy%20Truck/1995/G%2 ... Diagnosis/

I believe I found it. I also noticed a ground or power distribution block mounted behind the battery on the firewall, all of the nuts and the stud were rusted, I'll try and remember a wire brush tomorrow after work and clean that up too

Dielectric grease, use it. You mentioned it would crank slow like a weak battery, look close at the starting and charging circuits, behind the battery I believe you'll find fusible links, 4 IIRC and also look through the harness that runs across the cowl. I had similar issues a couple years ago in my '93 that is very similar I think to your '95.

WoodButcher wrote: ↑Mon Apr 29, 2024 4:53 pm Dielectric grease, use it. You mentioned it would crank slow like a weak battery, look close at the starting and charging circuits, behind the battery I believe you'll find fusible links, 4 IIRC and also look through the harness that runs across the cowl. I had similar issues a couple years ago in my '93 that is very similar I think to your '95.

The starting and charging circuits you mentioned might be the spot on the firewall behind the battery that is rusted....I noticed it yesterday and forgot the wire brush bad day at work I just came straight home....I'll take the nuts off and clean everything up then put it all back. I bought a new fuel pump real after work today but it wasn't quite hit enough to get it to stall out. Tomorrow will be in the 80s so easily hit enough to cause a stall if it's gonna do it still

Still stalling after replacing fuel pump relay although it only stalled out on me today once on the drive home and that was when I was sitting to wait for a train to pass for almost 5 mins. I've seen videos that mention the IAC and tapping it while running and if idle speed changes, that it should be replaced. The only thing is that it doesn't idle poorly and I get average gas mileage which is around 12-13 mpg last time I checked. Any other ideas before I go buy a fuel pump?

measure the fuel pressure