Fuel pressure issue - 95 Astro - please help (2024 Update)

Summarizing

Fuel/Ignition/Other? Please help

I have been trying to figure this out with no success. Can you guys take a look and offer any suggestions you might have?

Vehicle:

1995 CHEVROLET TRUCK ASTRO VAN 2WD Automatic Transmission 6 Cylinders 4.3L CPI 105,000 miles

Symptoms: The van always starts and runs fine for at least a minute or two. However after a short distance it will not accelerate properly and it will try to stall. As it progresses I might get some popping at the engine and eventually it will die. When I press the accelerator it acts like it wants to die.

It takes as much as 10 to 15 minutes of regular city driving to cause these symptoms or 2-3 minutes of driving under a load (when I hot-rod it). It does not seem to be directly related to engine temperature.

If the van completely dies, I can turn it off for 10 seconds then right back on and it definitely drives better (not completely normal). If I leave it off for 15 minutes it usually runs quite a bit better. Overnight and it runs normal when I first start it.

Parts Replaced: Leaky CPI (spider) Inlet outlet fuel lines (nut kit) Fuel Filter Fuel Pump and strainer Exhaust from O2 sensor back Drained the gas Ignition coil PCV Valve Tune up (plugs,wires,cap,rotor)(6 months ago) Oxygen sensor (6 months ago)

Current Diagnostic (I am a complete armature so some/all items could be irrelevant)

EGR (sticking) Tapping/ticking started after I removed/checked this. I am pretty sure I just need to take it off again and clean or replace. I do not believe this is my main problem because I took it off, closed the valve, and reinstalled without hooking it up. This test did not change any of the symptoms listed above.

Distributor I just examined the distributor and one of the plug wires and probes on the distributor was severely corroded; the rest were fine. I will get a new cap and wire tonight and check the plug.

Fuel Pressure Test with a fuel pressure gauge. After sitting overnight, turn key on and I get 62psi pressure (in spec). Turn key off and it holds 25psi pressure (there is no spec that I know of for this). While running it never drops below 50psi (in spec) even when it is acting up. While it is acting up and I accelerate the needle will sweep between 50psi to 70psi very fast. What concerns me is that after it is acting up and I turn the key off the fuel pressure instantly DROPS to 0psi. It this an issue? If I let the van sit for two minutes and turn the key on (pump on) then back off again it will still drop to 0psi. If I let it sit overnight it will again hold 25psi of pressure with the key off.

Codes The check engine light (service engine soon) does work, but does NOT turn on. I do not get any codes. To verify I rented an "Actron Super AutoScanner" and checked the codes. I do not get any.

I know I can monitor real time data with this device (scanner) but I do not know what to look for (suggestions?).

Do you guys have any suggestions on what to try next? I am about out of ideas and I am thinking about taking it to the shop. If/when I take it in, do you have and advice on what type of shop or diagnostic test I should ask them to run (or not to run)?

An engine needs thre things to run Air, Fuel, Ignition source Air is a given unless your covering the air cleaner with a bag. Fuel - about the only thing you didn't replace was the tank, so I would say your OK there

The symptoms point to a heat related failure. Some component is getting hot enough to shut down the engine. Since you still have fuel pressure when the engine dies it isn't a bad pump. It also isn't likely the EGR since they don't normally shut down an engine and then clear up when they get cool. They are either stuck open (which causes REAL bad idle on the 4.3 and an engine that will not idle hot or cold) or they don't work at all.

Ignition? You said you found a cruddy wire end. One usually won't do much but cause missfiring in that cylinder. I has a problem with the wifes 94 4.3 that was a bad set of plug wires. It caused massive missfiring but no real problem with running or acceleration. Just bucking under load. (common symptom FYI).

Bad plugs- Not likely since they fire OK when cold. Plus for the engine to quit they all have to stop working.

Plug wires- Same as above BUT they could cause crossfiring.

Cap - Usually causes missfires if the cap is bad.

Rotor - possible but not real likely.

Coil- very possible- it could be shorting out internally when it gets warm enough.

Ignition Module - possible for the above reason, but they usually just fail.

Computer - It's not showing codes which is not unusual for an OBD I.5 vehicle (oddball that GM used in 95 on some vehicles) they mainly show a code only when an item totally fails, unlike OBD II that can tell you that a sensor is just getting weak. It could have a bad connection on the main connection though.

Main wiring harness connection on the firewall - It has been a culprit a few times for heat related problems. It gets warm and the connection opens.

It is also possible that it could be a bad connection to one of the above components.

I think I'd elmintae fuel entirely for the most part and at least slap a gauge on that fuel pressure. Run it and shut it off see if it holds pressure. See what the presure is when it stops running for the hell of it.

Sure the EGR is carboned up inside?(it should be getting close by now).

This makes it sound like an injector problem to me. The only way it can bleed off the pressure is to leak somewhere.

Have someone turn the key while you look into the throttle body for gas pouring into the manifold. (it is throttle body design, not multi-port right?).

Just a guess but easy to test for.

Good luck,

Murray

Did you get the issue settled? Sounds like what happened to my 1988 Olds wagon. Rodent had chewed at the main wire harness under the car. It eventually caught on fire. Fire was put out. Harness replaced,ran fine. I guess some bare wires were touching the frame at times and really screwing up the main computer. Giving me all kinds of weird stalling.

May sound silly, but when was your last tune up? I spent hour after hour looking for a difficult answer for the crappy running motor. Turned out, I replaced the rotor, cap, wires & plugs......never better

Good luck

I finally got it fixed. I suspect it was the pulsator. I ended up dropping the tank and replacing the pump, threw out the pulsator and replaced with fuel line, replaced the main gasket and a missing o-ring on one of the fuel lines to the tank. I am not sure if the o-ring was lost when I dropped the tank or some other time.

It runs great now. Thank you guys so much for all you help and suggestions!!!!!

replying to daveg.01, Drewsky wrote: I have the same problem with my van same model w vin. Did you ever find the problem?

On Thursday, February 3, 2005 at 12:02:04 PM UTC-8, snipped-for-privacy@gmail.com wrote :

See if it is showing any codes, get an ODB II checker at auto supply that p lugs into a socket under the steering wheel. Zero fuel pressure is one thi ng, but there are many sensors that cause problems with computer adjusting fuel output. On my 2.8 93 Sonoma I have had problems with temperature senso rs causing similar problem, another one is throttle position sensor, but tr y first to see if computer can send code that you look up in book to see wh at's it thinks is wrong.

My 95 Astro Van is down It's been sitting for a long time I was using it to drag the road (Dirt) it started dying like it was a fuel filter, So i replaced it, it did same, I did get it to run enough to move it, so it blocked my neighbours view, of my hot tub, it set for a while The a fried with an S-10 told me his did same, and it was the fuel pump, So I replaced it, still not running I pulled the top of the plenum off and checked the injector it seemed fine The I got a pressure setup it goes to 60 psi pump goes off and pressure droppd to 40 psi then slowly down to 30 psi, and a very slow drop to 20

Fuel pressure is lower on a fuel injection car than with carburetor I read once. With my 93 Sonoma, past problems were most often with sensors in the fuel injection and smog system. I have in the past replaced the fuel pump in the tank (did so by raising truck bed to gain access), but first better to invest in a code checker, auto suppliers have them for around $25. Sensors regulate fuel, it could be throttle position sensor, or temperature sensor (when cold it tells computer to use more fuel for same rpm). Under the dash is a socket, you plug in the checker, it begins flashing a code with a light in the instrument area. There are 6 to 8 sensors. Look up in a repair manual of that car, and it will tell you how it is done and show the code meanings for you to localize what the problem is before spending too much.

When engine quits and won't start, try putting a little gas in throttle body and put air filter back on (to avoid fire), then try starting to see if it runs for a few seconds. That might be good test to know it isn't getting fuel during those situations. Sometimes hard to know if fuel or electrical is problem. I think my 93 sonoma was acting up, cutting out at times a few years ago, recalling as you mentioned fuel pressure. Someone told me that fuel pumps go out gradually, used to be easy to replace too. The in-tank variety can be hard to get to. A van might have a cover on the van floor to access the top of the tank, and even allow you to remove the pump assembly from the top of tank--a ring that turns unlocks some tabs and then pump assembly lifts out, that part fairly easy. New pump fixed my cutting out, cost about $70 online. When stumped, I go to a repair shop and get estimate how much to diagnose problem. They used to do that for around $100. Then fix it yourself from their advice. They have better equipment and are used to solving mysteries.

This first sentence is total bullshit so ...

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