Starts fine, drives fine, bucks, sputters and dies randomly?

[tayman]

The fuel pressure doesn't move at all with revvs. It just stays about the same. Bad regulator? clogged line? I'll try pulling the vac line off the regulator and see if it makes a difference.

CPS went bad in just months? that's quick... I also have occasional no-starts... but starting fluid takes care of that.

Cleaning the CPS consisted of removing it from the bellhousing and wiping the grime off of it.

I have not done a TPS check... I may just replace it, seeing how it's 21 years old 'n all.

Disco'd the vacuum line to the fuel pressure regulator, and it popped up real sharply. RPM's still do nothing to effect pressure.:banghead:

 

[Ecomike]

Is there any vacuum in that vacuum line? If not fix that. If there is good vacuum in the vacuum line, it sounds like the FPR is bad. If you can smell gas at the vacuum line / FP regulator nipple connection then the FPR diaphragm is bad, and leaking gas into the vacuum line!

21 Year old TPS needs to be retired!

Fuel pressure at idle is the same as at 3000 rpm. Only change is temporary (1-2 seconds) during rapid acceleration or deceleration and is caused by the changing vacuum at the FPR!!!!!

My CPS was bad from the very start, out of the box, it was bad one out of 5-10 start attempts, random, due to due a loose wire (cold joint, like a bad ground) connection inside the CPS sensor. It worked well enough and often enough to make think I had a second problem!!!

 

[cruiser54]

Starting fluid takes care of occasional no starts?

 

[tayman]

Starting fluid takes care of occasional no starts?

Yeah, it does for me. Kind of a pain when they happen like three times in a day though. Just shoot it in the intake, and viola.

I'll check on the vacuum at the FPR and post back.

 

[Shorty]

Starting fluid takes care of occasional no starts?

definitely sounding more and more like a fuel delivery problem-- starting fluid wouldn't help at all with a bad CPS (you wouldn't have spark, either)

 

[Ecomike]

I wonder if starting fluid would ignite with out a spark (?), thus raising the RPMs enough to kick in a weak CPS signal?

I never use the stuff. Tried it once on a flooded engine before I figured out what was going on (float stuck open and dumped 1/2 gallon of gas into the crank oil, old carb engine, 78 Dodge), never tried it again, LOL.

 

[cruiser54]

I wonder if starting fluid would ignite with out a spark (?), thus raising the RPMs enough to kick in a weak CPS signal?

I never use the stuff. Tried it once on a flooded engine before I figured out what was going on (float stuck open and dumped 1/2 gallon of gas into the crank oil, old carb engine, 78 Dodge), never tried it again, LOL.

It will on a diesel with a compression ratio of over 15:1. Wouldn't count on it igniting at cranking speed on a gas engine.

 

[tayman]

definitely sounding more and more like a fuel delivery problem-- starting fluid wouldn't help at all with a bad CPS (you wouldn't have spark, either)

Which brings us back to fuel?

I checked the vacuum line at the FPR and it's got decent vacuum. Sticks to my finger nicely, anyway. Disconnected from the regulator the pressure pops up about 9psi and the idle speed raises.

That's all fine and dandy, am I wrong?

Are we back to the TPS?


Another thing I forgot to mention, I can smell something along the lines of fuel vapor in the engine bay. I know I don't have a fuel leak.

 

[cruiser54]

No, we're still on fuel delivery. Get a fuel pressure gauge and check the fuel pressure at the fuel rail. 31 psi at idle, 39 psi with the vac line pulled from the FPR.

 

[tayman]

look at the top of the page... Did it already. it's pretty much spec.

 

[cruiser54]

Perhaps weak spark or intermittent fuel pump issues? What kind of spark do you get if you pull a plug and ground it out while cranking the engine? Should be blue and snapping, not orange. Have you ever unbolted the coil from the ICM and cleaned and tightened the contacts between the two?

 

[Ecomike]

The TPS is 21 years old. It must be part, if not all of the problem.

Also, the FPR, may have a small diaphragm leak (source of the gasoline smell perhaps?), that lets excess fuel into the intake on high vacuum.

Are the fuel injectors also 21 years old?

 

[tayman]

The TPS is 21 years old. It must be part, if not all of the problem.

Also, the FPR, may have a small diaphragm leak (source of the gasoline smell perhaps?), that lets excess fuel into the intake on high vacuum.

Are the fuel injectors also 21 years old?

Alright, that's worth trying. I'll get a TPS, and a new FPR?

Injectors could very well be 21 years old also... though they HAVE been cleaned within 6 months or so. I guess it wouldn't be a bad idea to replace those too.

 

[tayman]

Perhaps weak spark or intermittent fuel pump issues? What kind of spark do you get if you pull a plug and ground it out while cranking the engine? Should be blue and snapping, not orange. Have you ever unbolted the coil from the ICM and cleaned and tightened the contacts between the two?

I have not cleaned the Coil/ICM contacts... I should probably do that too.

Haven't checked spark yet, but I don't think that's the issue, because for the occasional no-starts, starting fluid works fine. So it's got at least DECENT spark... and a new distributor, cap, rotor, and wires.

 

[cruiser54]

A new TPS, installed and adjusted correctly, certainly would not be a waste of time or money IMHO. It could end up being a time saver in this instance.

 

[Ecomike]

The OEM, original fuel injectors were notorious for leaks at the split case in the housing, and have caused fires!!!!

Good idea to clean and tighten the clips on the ICM to HV coil contact area too.

 

[tayman]

The OEM, original fuel injectors were notorious for leaks at the split case in the housing, and have caused fires!!!!

Good idea to clean and tighten the clips on the ICM to HV coil contact area too.

Alright, good, good... I have stuff to do on my day off tomorrow!

 

[NorCalChris]

Taylor, I have a few sets of stock injectors out at my grandpas house. You can have them if youd like, I know which sets had a leaking injector and which didnt.

 

[Shorty]

definitely sounding more and more like a fuel delivery problem-- starting fluid wouldn't help at all with a bad CPS (you wouldn't have spark, either)

Id put money down on a CPS.

still leaning toward something else

 

[Ecomike]

Bad IAT or CTS (or MAP, or ECU for that matter) can screw with the Air/fuel ratio the ECU thinks is needed during crank/start up, which might be overcome by starter fluid. I would not read too much into the starter fluid here, based on the rest of his data so far.

At this point he should be testing all the sensors with a volt/ohm meter, but he seems to be moving onto swapping 21 year old suspect parts out, rather than bother testing them, which may be the smart thing to do here, if he wants a reliable rig.