last week I picked up a 92 RS 3.1, auto. The car has 108,500 on it. The guys said the intake gaskets were done not too long ago by a buddy and the fuel pump is newer. Anyways the car ran fine, a slight rough idle in gear, but that's it. Well I got the car emissions tested and it passed with a leaking Flowmaster cat back so all was good. Well later Monday after drving her all day and runing fine, she stated to sputter and cut out bad when I pess the gas, but if I let up it runs fine. Also when it's does this if you hold the gas it will stall, but if you put the trans in N or P it runs great and will free rev nice and smooth as high as you want. If you let the car sit over night and then start and drive it the problem is gone till it warms up. I'm thinking maybe fuel pump since my TA felt and sounded just like this when it's fuel pump went bad, but it cut out in P and N as well. What do you guys think?

 

Check your fuel filter before you go straight for the pump. Any ses codes? Hows your fuel economy?

 

Sorry forgot-no SES light on or any dash lights for that matter. I would say the MPG is not bad, but only had the car a week and it's not a DD so hard to say on the MPG.

 

No SES lights or dash lights at all? even when you first start the car? it should at least flash briefly when it's first started. if it doesn't, you may need to replace the bulb. The reason I asked about the mileage is because bad mileage could mean a bad o2 sensor. Definitely can cause a rough idle. Not so sure about cutting out though.
Honestly, my fuel pump did the same thing when it was going out, but I never tried it in P/N. I'd still def check the fuel filter first. Does the pump whine at all right before this starts happening? Mine started screeching like crazy right before the car started dying. would sit for an hr and limp it the rest of the way.
I'm gonna still lean towards something easier, a sensor or something, just because it stops in P/N. Something mechanical like that would cut out in any gear.

 

I would also definitely consider a standard tune-up. plugs, wires if necessary,(check them closely, and if there's any question just replace them), cap, rotor, o2 sensor, and fuel filter. That way you can eliminate the simple stuff first. and if that SES light isn't working, fix that with the tune-up.

 

If no codes:

Check fuel pressure at rail.

At Idle, part throt, WOT(if possible)


If that all checks out head twards the spark troubleshooting.

 

All the dash light work and kick on at start up like they should, what I meant was there is no lights on when the car is running or acting up. When the car starts the sputter crap it acts just like my TA did when the fuel pump went out in it. I cannot notice if the pump is makng nosie when the iusse starts since the car has a Flowmater on it plus the mid pipe is rotted by the axle so the exhaust is all you here back there. When I turn the key to run you can hear the pump kick on and prime like it should and it dones not sound funny to me, but not as good as my new AC Delco pump in the TA. IDK guys this one has me stupped and with it being so cold here now and all the snow we just got the car is sitting under a cover in the drive way. By the way before the car does the sputter think it seems like it's holding back when you punch it-like it does not cut out, but just kinda hangs there then picks up speed-again my TA did that when the pump was on the way out.

 

Only way to know is to test the fuel pressure. Less than 37 PSI running indicates a bit of an issue in the fuel system.

 

Yeah I want to, but it's been cold and snowy here so the car is parked under the cover. I will have to do a driveing fuel PSI test as it only acts up once warm and while drivng. I guess tape the gauge to the windshiled and see what it does. It's just so odd to me since it only sputters while driving after warm-it's fine in P and N.

 

on my iroc the thing would rev up and down in p/n but once in gear and opening of the throttle would make it die .

it only had 18 psi of fuel presure ,


best bet is like mav said tape a fuel presur egauge to the windshield and take it for a drive till it acts up and verify that u have low fuel presure , if u dont then its something else

 

Also do a resistance test on the fuel injectors...

For a 90-92 car, any injector reading below 11.8 ohms needs to be replaced, period. Easiest way to do this is first when cold, unplug the front connector on the injector harness (6-way connector next to the thermostat housing), and probe the pink and blue and green wires with the meter. Should come out to around 4 ohms per bank (measuring 3 injectors at a time). 6 ohms or more per bank indicates a bad injector (or more than one). And test again when the engine is hot.

Could also be partially clogged injectors as well.

 

So how many ohm's per bank is good? I still say it's the fuel pump as it acts just like my TA did when it's pump went out, and it comes as goes like the TA did.

 

Ok I have not had a chance to check the car out or get it checked out as the wether has been crap here the past few weeks. I did not have new thought. My exhasut is rotted out, but it's very bad right over the rear axle on the top of the bend. Do you think it could be cooking the fuel tank? Some exhaust does come out the tips, but alot leaks under the car. Also I was trying to hear the fuel pump this weekend and when I opened the fuel door it had a fuel smell-like more than most cars. I know the cap is good as the car passed emssions testing the day the issue started and the fuel cap passed it's test. Any thoughts or am I crazy?

 

I had an 87 2.8 with the same prob turned out there were sep harnes conectors for fuel inj for left and rt side of the motor pas side was loose sometimes only ran on one bank . hope this helps

 

New intermediate pipe is cheap...

There is a fuel tank pressure relief valve right next to the driver's side rear wheel. It looks like a white bell. Last I heard, there may not be any replacements, so you may want to poke around at a junkyard to see if you can find one. It's either that or you have an issue with the charcoal canister and it needs to be replaced.

 

Is that valve that your talking about an issue if it's bad-like running wise? Yeah Autozone has the intermediate pipe for like $36.00. The flowmater that is on the car is rotted and well and it's all welded together-the only place the cat back bolts is to the cat. I can make my own cat back once I get a new intermediate pipe. It's going to be nicer this weekend so I might get to mess with the car some. Here is a pix of it by the way

 

I have an update. It's been so cold here that I have not had a chance to work on the car. There is a good shop about a 1/4 mile from my house that has done some work on my TA and my last truck. I called him and he said he would diag the car for $89.95 no matter how long it takes. I took the car to him yesterday and it would not act up most of the day-they put the scanner on it and no codes, all sensores working good, fuel PSI great, then after running about a 1/2 of tank of gas out it started acting up. They checked the fuel PSI when acting up and still great. So after poking around allot they found the plug wire boot on the front cyl on the passengers side had a slice in it-bad slice, but you could not see it just by looking at it, also the vac line elbow to the fuel reg had 2 holes in form from a mouse or something. They put a new wire on and vac elbow and the issues stopped. The car runs better, but still not as smooth as I like. Once it warms up I'm doing a full tune up. But for $104.00 the car os running and alot of things checked out. They also said it's a very soild car, but I knew that.