Vacuum Line Replacement Issues - Sportmachines Kit.

[JNR]

Hey there, I have a weird puzzle on my hands and wanted to get some input. Had my truck since 98 and this past year it started running rough so parked in the garage and only driven for short distances. Cruise had stopped working and the ac controls didn’t hiss any more and stopped working indicating lack of vacuum. The truck would start and run, just not well.

Fast forward and I went ahead and ordered a new vacuum line kit from Sportmachines. Received the kit last week and pulled the truck out yesterday to begin the job. Very nice kit and really a simple replacement job. In the process of replacing the lines I did find that the vacuum line feeding the charcoal canister had popped off which was likely the root cause of my issues. Regardless I went ahead with the install of the lines as they were all pretty old and weathered.

The Sportmachines silicone vacuum line kit is pretty straightforward and other than having to remove my battery and tray to get to the vacuum ball it was really an easy mod. I did disconnect a modular electrical connector that sits behind the FPR to give me clear access to the plastic line coming from the HVAC through the firewall. This got reconnected at the end of the line installation. No drama here just a quick connector unplug and re-plug.

Expecting the truck to start and sing like a course of angels, instead it wouldn’t start. It sounds like it almost wants to fire but won’t. Every now and then I get a chug out of it. I checked all of the lines again and there really is no easy way to goof it up and they are all on the proper fittings. I disconnected and reconnected the electrical connector again but no dice. I wondered if the check valves were installed correctly in the harness and thought I would post some pics to see if anyone would comment.

It seems to me like the truck may not be getting fuel although the vacuum line from the back of the intake is in place and secure as is the line at the intake and the map sensor. I had replaced the stock fpr with a billet adjustable years ago and having an fpr go out coincidentally seems unlikely. I am going to drag out my fuel pressure tester to see what it shows.

Here are some pics.
First pic is the full harness with all extra pieces, second is a close up of the main harness that feeds the EGR solenoid and the cruise control. Hose pointed to the right feeds back to the firewall. The last pic is the hose and check valve connecting the intake to the charcoal canister. The bigger hose connecting to the canister side. I am guessing that the check valves should allow vacuum draw from the intake but check pressure in reverse. In this case they would all either be correct or would all be wrong. Thoughts and experiences appreciated.
First pic is the full harness with all extra pieces, second is a close up of the main harness that feeds the EGR solenoid and the cruise control. Hose pointed to the right feeds back to the firewall. The last pic is the hose and check valve connecting the intake to the charcoal canister. The bigger hose connecting to the canister side. I am guessing that the check valves should allow vacuum draw from the intake but check pressure in reverse. In this case they would all either be correct or would all be wrong. Thoughts and experiences appreciated.

 

[1blkc4]

I just replaced the lines using the same kit you cant go wrong mine had some cheap silicon lines that looked like an hour glass .My upper intake manifold gasket was leaking too the part of the gasket was gone both of these problems created high iac counts just follow there diagram .

 

[wildphil]

It is possible a connecter or wire may have been knocked loose or broken while the vacuum hoses were installed. Like, say to the fuel injector harness or even the white and red wires to the distributor. It is tight in the engine compartment and those trucks are getting old. Those wires can break pretty easily.

 

[JNR]

Yes agree, the wires are all getting pretty brittle. I am going to do some closer inspection of the wires and a few additional tests tomorrow using my fuel pressure tester and mityvac. Although the issue could be electrical even though I have cranked the motor over repeatedly I don’t smell any fuel at all. On top of that my brake pedal is firm to press evenWhile cranking which tells me this is likely a vacuum leak somewhere.

I will follow up with what I find.The Sportmachines hose kit really is top notch so pretty happy with that.

 

[DaveP's Ghost]

If all the vacuum lines on the engine were left on your bench, it will still start and run. Not well, but it would start. So vacuum lines are not the cause of the no start.

Does the tachometer indicate RPM when cranking? If = No, check the two connectors at base of distributor, and both connectors at the coil.

The other connector of interest is the 3-wire at the pass rear side of the intake. Green, blue, and pink/blk wires. This is for the fuel injectors. With the key = ON, check the pink/blk wire at the #1 injector (easiest to access with the engine assembled) for battery voltage. If = NO, this is the cause of your no start (no voltage to injectors). Check the ECM fuses A&B or 1&2, they can be labeled either way.

There's some ideas.

 

[JNR]

Had a good morning today. I pulled the charcoal canister and checked the line with the mityvac and everything looked good with vacuum against the check valve. I replaced that line and then pulled the cruise control line which is on a different check valve circuit and when I tested it I couldn’t get it to hold pressure against the check valve on the main harness.

I replaced the cruise control vacuum line and pulled my battery so I could get to the vacuum ball line through the inner fender. Pulled that line and checked and I could get vacuum to hold and that’s the same circuit as the cruise. Carefully replaced the line onto the ball and went back to the cruise line again and this time after some pump up I could get it to hold. Pulled and replaced the cruise vacuum line and reinstalled the battery and connections.

The truck started right up and my hvac and cruise are both working again!

Based on what I did this morning I can only assume when o pushed the line onto the vacuum ball yesterday I must have pushed it in between the nipple and the edge of the vacuum ball. I did that blind through the fender well with the battery tray and ball bolted back in place and I was “confidently” installing by feel.

At any rate the Sportmachines Kit was flawless and the installer not so much, and proof positive that even a simple “no brained” task can go awry if you don’t check yourself!

 

[JNR]

One other note was that I did not mess with any electrical wires this morning, just the three vacuum lines at their end points which were not close to any wiring.

Thanks for everyone’s feedback regarding this post, it was appreciated.

 

[DaveP's Ghost]

One other note was that I did not mess with any electrical wires this morning

Glad to see it is running, but the vacuum lines were not the cause of the no start.

You've owned your truck a long time. You haven't driven it much lately. There is a possibility that there is another condition developing that is causing the no start. You mentioned "sputter" and "acts like no fuel pressure". These are both symptoms of no ignition pulses caused by a failing or out-of-spec distributor pick-up coil. It is INSIDE the distributor, white and green wires, not the external ignition coil that makes the sparks. Over the years I have solved numerous no starts by replacing the distributor pick-up coil.

Here is a quick test for the pick-up coil. Next time it won't start, try this:
Turn key to RUN, fuel pump will run for 2 seconds and stop.
Blip starter just enough to move distributor, and stop.
Listen for fuel pump: It should be running for 2 seconds, then stop.
Did it? Yes= distributor sent reference pulses, pick-up coil is OK. No= No reference pulses sent. Replace pick-up coil.

If you don't have refrence pulses, do not fall for replacing the Ignition Control Module, and not the pick-up coil as well. In my experience I have only found 1 bad ICM, but numerous pick-up coils that were causing no-starts. Replace BOTH, if this no start returns.

 

[JNR]

I appreciate the extra info. My fuel pump is on a separate racetronix power ckt. harness and it does spin up when I turn the key to the on position and once pressurizes the fuel rail it stops. That’s pretty consistent. I can do that test to see what happens. Basically activate the starter after the FP pressurizes, stop, and then listen to see if it re-pressurizes.

Thanks again for the insight.

 

[Jay92Ty]

Glad you figured it out. I F***ing hate these trucks . I would like to add one thing with the vac line from SM. They are awesome, fit well, great quality, etc. I could never say anything bad about the kit, in fact like most will agree I would highly recommend it. That being said, I installed my kit probably about 3-4 years ago and just days ago I was chasing a vac leak. Turns out it was the 2 small larger hoses that connect to the check valves ( your second pic) . One side is a smaller hose than the other. It was leaking on both of them ( the two larger one on both check valves). I replaced the zip tie with a larger tie and still leaked. I then removed the 2 small hoses and borrowed 2 small ones from the other vac lines and boooom...problem fixed. AGAIN.. just something to consider in the future.

 

[JNR]

Glad to see it is running, but the vacuum lines were not the cause of the no start.

You've owned your truck a long time. You haven't driven it much lately. There is a possibility that there is another condition developing that is causing the no start. You mentioned "sputter" and "acts like no fuel pressure". These are both symptoms of no ignition pulses caused by a failing or out-of-spec distributor pick-up coil. It is INSIDE the distributor, white and green wires, not the external ignition coil that makes the sparks. Over the years I have solved numerous no starts by replacing the distributor pick-up coil.

Here is a quick test for the pick-up coil. Next time it won't start, try this:
Turn key to RUN, fuel pump will run for 2 seconds and stop.
Blip starter just enough to move distributor, and stop.
Listen for fuel pump: It should be running for 2 seconds, then stop.
Did it? Yes= distributor sent reference pulses, pick-up coil is OK. No= No reference pulses sent. Replace pick-up coil.

If you don't have refrence pulses, do not fall for replacing the Ignition Control Module, and not the pick-up coil as well. In my experience I have only found 1 bad ICM, but numerous pick-up coils that were causing no-starts. Replace BOTH, if this no start returns.

Just a quick update. I did the test letting the FP pressurize the lines then giving the starter a quick blip to turn it over without starting and then released the ignition switch and I could hear the FP re-pressurizing. Bottom line is that I don't think the no-start condition was related to the pick-up coil if that test is conclusive. Do you think the ICM could cause an intermittent issue like that?

For some background prior to installing the vacuum line set, I had two types of issues that drove me to replace my vacuum lines. These were things that existed before the post vacuum line "no start condition" showed up.

1) The first issue was that my cruise control and my HVAC controls both quit working which were indicating a common vacuum line issue. After replacing the vacuum lines and getting the truck running both the HVAC controls and cruise control are now working again. Those issues resolved.
2) The second problem was that the truck was running very rough with a miss, which could also have been related to a vacuum leak problem as well. After replacing the vacuum lines the truck is running better but still a bit rough though. I had a set of new CR42TS plugs I have had sitting on my tool bin for over a year so I gapped and installed them still using the current cap, rotor, and plug wires. All of the old plugs looked excellent, and had an even burn with no oil fouling or carbon build-up deposits. I was actually a bit surprised that they looked that good as its been a couple of years since I changed them last. With the new plugs gapped and installed the truck starts up as before but still has an intermittent miss and I am getting ready to replace the cap, rotor and plugs which I always do with the plug change-out anyway.

If the cap, rotor and plug wires don't do the trick I am considering the following:

Ignition Related
1) Bad ICM?

Potential fuel related issues.
1) Fuel filter has been replaced a year or so back when I replaced the fuel pump again.
2) Check fuel pressure and adjust as needed (doing this as a baseline anyway)
3) Inspect and replace w/clean injectors
4) Possible intake manifold leak? The motor was replaced with a GM ZR9 long block at 72K miles due to a rod through the original block so the intake has been off and re-installed. That was around 20 years 60K miles ago.
5) Replacing the O2 sensor (if I can get that bugger off! ). Already had this in the toolbox for replacement at some point.