Loss of power when accelerating.

[scott'srafro]

Howdy ya'll,

93 Astro W-vin...AWD 4.3L with 140,000 miles.

After I drive for 5 minutes and come to a stop, the van will start hesitating upon acceleration. I can finally get up to good speeds but then the next time I slow down, I lose all power while accelerating back up. The van shuts down, I pull off the road...turn it off...turn it back on...and then it runs great for 5-10 minutes. Then it will lose poower again and I start the process over again.

I put a new fuel pump in it 3 months ago but the mechanic says my fuel pressure is fluctuating. He thinks I put in a faulty fuel pump. He also says I have a minor intake leak. SES light pops up after idling for a few seconds. EGR, rich exhaust, idle air control. I pulled my EGR 3 months ago and there was no carbon chunks. I noticed my coolant was extremely low also.

Where do I start? Thanks!

[letmecheck]

I have a '93 Safari with the W Code engine, 118K, mine seems to do the same type of thing only less severe. I've given the van a tune up about 10K ago, just put on a new catalytic converter and exhaust system, and still get the 'bog down blues'. I don't know what it could be at this point. When the van is cold (under thermostat open temp) and I punch it, the van takes off, plowing through gears like she's brand new -- this van is fast! Once I hit that 200 degree mark (digital dash), and let's say I'm going 60mph on the freeway and want to kick it up to maybe 70, I gun it and she drops into 2nd gear and the RPMS go nuts except I go nowhere. Sometimes feel like I'm slowing down, and the van sounds as if it's being choked. If I let off the gas and let it go to third gear and run about 2500-3000 rpm (guess), the speedo climbs. Same thing happens at 30MPH. If anyone decides to reply to this post, do you have any suggestions for me? I've replaced the fuel pump at 105K, the trans fluid was replaced over 60K miles ago. I checked it, nice and pink and at the correct level when hot in park, but I don't know what the smell is supposed to smell like. Perhaps a fuel filter change? I don't know where it's located on this van. Hopefully that GM technician will read this post and be able to help. One more thing - the shop that installed my exhaust system said the computer did not have any trouble codes, and I never have my Check Engine light come on except for when I crank 'er up. Thanks!!

[AstroLover]

My 1993 has 178,000 and change. I have replace the Central Multiport Fuel Injection Unit twice. In MN we have gasoline that has been modified and this causes the Fuel Injection Unit to develope leakage in the regulator portion I beleive. GM has redisigned the unit several times and therefore there are three or four part numbers. The old part numbers may still be sold in the gray market through some Delco channels but officially the GM parts center should be selling only the up-level ones. The symptoms are rough idle, hunting of the idle, poor fuel economy and funny smell when running. Also, when you start the vehicle, it may take extra cranking to get it to start. Another common problem on these I'm told are the fuel tubes that are inside the plenum on top of the intake manifold get leaks from rubbing together. My friend is an ASE Master Certified mechanic and has noted both these as common troubles. One easy way to check it is to do a fuel pressure test and BE CAREFUL as the fuel can leak from the connections while attaching and disconnecting the pressure guage which is a special tool but well worth the cost. I beleive my pressure runs at about 55 to 60lbs and when you turn off the van, it may leak down a bit but it should hold if the CMFI, lines and fuel pump are OK. The symptoms are all variable depending on how bad the failure is. Bad news is if you do this yourself the parts alone are $500.00 or more. Good Luck...

[AstroLover]

Originally Posted by AstroLover

My 1993 has 178,000 and change. I have replace the Central Multiport Fuel Injection Unit twice. In MN we have gasoline that has been modified and this causes the Fuel Injection Unit to develope leakage in the regulator portion I beleive. GM has redisigned the unit several times and therefore there are three or four part numbers. The old part numbers may still be sold in the gray market through some Delco channels but officially the GM parts center should be selling only the up-level ones. The symptoms are rough idle, hunting of the idle, poor fuel economy and funny smell when running. Also, when you start the vehicle, it may take extra cranking to get it to start. Another common problem on these I'm told are the fuel tubes that are inside the plenum on top of the intake manifold get leaks from rubbing together. My friend is an ASE Master Certified mechanic and has noted both these as common troubles. One easy way to check it is to do a fuel pressure test and BE CAREFUL as the fuel can leak from the connections while attaching and disconnecting the pressure guage which is a special tool but well worth the cost. I beleive my pressure runs at about 55 to 60lbs and when you turn off the van, it may leak down a bit but it should hold if the CMFI, lines and fuel pump are OK. The symptoms are all variable depending on how bad the failure is. Bad news is if you do this yourself the parts alone are $500.00 or more. Good Luck...

Forgot to mention, intake manifold leaking water into engine on front and rear corners where the manifold bolts to the head is also a common problem. If you're losing coolant with that many miles, check the oil for milky color and raised level. VERY critical to catch this early.

[letmecheck]

I don't know how this answers the problem.

[mrrob]

Silly Question, but after changing the fuel pump, did you change the fuel filter too?

I had an Astro Van that the customer had changed everything, Fuel pump, TPS, Cap, Rotor, Wires, Plugs, Module, Pick Up, he said he thought it ran a little better., but still bogged and stalled, lack of power.

I said what about the Fuel Filter?

He said I think that was changed!

It Was Plugged Solid....Replaced Filter Now Runs Great!

Just A Thought..Good Luck.

Mr.Rob

Lic Mech Auto/Truck/Trailer Ect....

[letmecheck]

I have what sounds to be exactly the same problem - I have a 1993 GMC Safari 4.3L CPI "W" with 119K, replaced exhaust system including cat at 115K, cleaned EGR valve, and ran seafoam through the engine crankcase & fuel tank. No codes come up when checking except the ol' 12, 12, 12, 12, 12, 12, ......etc.

When I start this baby up in the morning and open it up it takes off like a bat outta hell. As soon as it hits operating temperature, it seems that all of a sudden I have a lawnmower engine or something under the hood. The trans drops into a lower gear, and the engine kicks up, but it goes NOWHERE and always slows down. If i push the pedal juuuuuuust a little bit it will accelerate - albeit very slowwwwwly. Anymore pedal travel , let's say over 3/4" - it's done, struggling to even maintain speed.

No codes. Nice computer.

Anyways maybe someone has fixed this already! Help!