87 V10 TBI 350 Questions

[Kapdin]

Hello Gents, long time no see. I have since added a 1987 V10 Silverado to my collection of squares.

How I Found Her!

You must be registered for see images attach

After A Little TLC!

You must be registered for see images attach

So I am very limited on cash at the moment so all my testing and tinkering has been very budget minded. It is completely original (as far as I can tell) except the 2" suspension blocks. On that note the extended U-bolts used to hold thos blocks were one size to small in diameter and 3 out of the 4 were striped out and sloppy loose. I have since replaced them with the right ones.

I have ran all the RPO codes on this truck and its FULLY optioned Silverado which include the L05 engine (supposedly 210hp - 300tq) along with 3.73 gear option instead of the standard 2.73's most came with (SUUUPER excited about that one). The power windows and locks still work (although a little sluggish) but the seat is about shot and the dash has seen better days.

So here are a few questions for you TBI guru's. I have the dreaded "Surge" but mines not JUST at idle like most I have read about so I am almost certain mine has to do with either a week fuel pump or a leak in the fuel system. But since I do not have any funds for this truck at them moment I cannot purchase a fuel pressure gauge.

Actron CP7817

You must be registered for see images attach

So my first question, does my 87 have 2 fuel pumps (one in each saddle tank)? Or how does that work with two tanks?

I have also read that just about every other sensor can cause a surge problem so hear is what I have noticed doesn't work. First I know oil pressure tells the fuel pump when to turn on so will the fact that my oil pressure gauge pegs out cause a problem (assuming the sending unit is on the frits)?

You must be registered for see images attach

You must be registered for see images attach

Second I have also read that the temp "Sensor" not "Sender" can cause problems also but not sure how to tell if the "Sensor" isn't working when its the "Sender" that talks to the temp gauge?

You must be registered for see images attach

And last I have heard if a EGR valve is stuck it can cause the same but how (without replacing) do I test it? I have pushed on it and it moves.

You must be registered for see images attach

So now a few things I have fixed and a few I know have been replaced.

1. I have pulled the IAC valve out and cleaned it and looks in good shape.
2. I have replaced a bunch of vacuum hoses that were shot and a few just because. (I have not hooked a vac gauge up yet but when I do were is best place to hook into?)
3. I know the TPS has been replaced.
4. I have replaced the Fuel Filter.
5. Exhaust is manifolds into single aftermarket muffler (no cats).

So knowing all this if I had to put all my apples in one basket what would I check/ replace first?

 

[Georgeb]

Start here. I also fought this issue.

http://www.gmsquarebody.com/forum/showthread.php?t=13089

 

[Georgeb]

And also here
http://www.gmsquarebody.com/forum/showthread.php?t=13052
I touch on it off and on as I go.

 

[Kapdin]

Thanks for the links George, I have read over your threads and it is a good guide line. I feel like your problem may have been a little more involved than hopefully mine is. I will be tinkering on my truck this evening and hope to get the easy checks out of the way and I just have a hunch that its a fuel pressure problem of some kind. Again does anyone know if I have a fuel pump in each tank? Can I just flip tanks to see if the other pump is better? or does one tank have the pump and it pulls from the other tank? I have found wiring diagrams that show a pump in both tanks.

 

[Georgeb]

Yes, you have a pump in each tank.

 

[Kapdin]

Thanks I appreciate that info.

 

[Kapdin]

So I replaced all my vac hoses tonight and I got around 17-18psi but it was surging while I was doing it. So I also checked the timing but could not find the wire to unplug to get it to 0 degrees but at normal idle it seems to be right about 3/4" to 1" to the left of the gauge. I did however switch fuel tanks but the truck instantly dies. I repeatedly switch tanks till I was satisfied that it just has no fuel when I hit the switch. So I did get under it at this point to inspect the selector valve and saw this.

You must be registered for see images attach

You must be registered for see images attach

I did proceed to take it for a short cruise and after running it for a while and getting it up to temp its seemed to run worlds better but I could still tell something was off. Has to be a fuel problem doesn't it? Any suggestions would be great.

 

[Kapdin]

I forgot to mention, I unplugged my MAP sensor and the truck seem to idle great although I could defiantly tell it was running really rich that way.

 

[Georgeb]

Your timing plug is located right next to the steeriing column on the engine side. It's a single wire.
Ps I would set it at at least 6 deg btdc

 

[r67northern]

Have you checked the temperature sensor on the top of the engine? Sorry if I missed that earlier in the posts. I had similar problems and that had failed (apparently it is common to fail and causes the engine to think its operating temperature is way off, hence effecting the fuel air mix).

Since you unplugged the MAP sensor and things got better I'd think it is unlikely to be a cracked distributor but that could be another issue.

If you go after the temp sensor, grab a new set of leads and connector too. Those are known to be problems too as I understand it.