1994 1500 suburban with timming issues

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bandit2090

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Ok sorry if this has come up. I searched the forum and didn't find any helpfull post. I recently purchased the truck and shortly after the head gasket went. I have replaced the head gaskets and all other gaskets along the way. Now I can't get her to time properly, I have used both the gun and a vac gauge and both ways I can get it too run smooth but the second I put her in gear she dies. We have replaced the distributor module,pcv,iac. It has also had a full tune up including plugs wires cap rotor. We also installed a set of pacesetter headers the shorty plugs too fit. Kinda confused haven't had this problem before and she ran good even with the blown headgasket. I am at a decent amout of elevation but whenever I get her to run and check the marks she sits at 8-12 instead of 0 and this is with the advanced disconnect both connected and disconnected.
 
I went and got a fuel filter today and replaced it. Also replaced the temp sending unit.when I pulled the fuel filter the lines started to auto siphon and I got a nice gas shower. Could this indicate that the diaphram in the fuel pump is torn thus causing my issue.
Thanks for your help!
 
I believe you may be right about the FPR - it's worth a look - if you remove the vacuum tube and find fuel - you've found your problem.
 
If it was running fine before the work you did, it has to be something not put back correctly.
Did you have to remove the distributor to pull the heads? Maybe you are off a tooth. Set everything to TDC and see if the rotor is where it ought to be.
 
We have gone through everything and double checked everything. the dist was removed. The whole top of the motor was removed for the head gaskets. However it runs better than it did before it just won't stay running. Also tdc has been checked more times than I can count. We have also removed the dist. multiple time to move it forward or back and both ways make things worse. I'm going to check all vac lines ser if I fond gas anywhere it should not be.
 
Are the advance weights in the distributor okay. Maybe they got messed up while it was out.
I don't think throwing parts at it is the answer if it ran fine before.
 
As far as I can tell they are ok. I did have the dist. Module tested and it was bad so i replaced that first. Visually the dist. Is in good shape, no wear marks that I can see.
 
Funny that the module tested bad when it ran fine before the repair. I'm out of suggestions.
 
I know I'm stumped. I'm going to continue trying everything I can before I take it too a shop.
 
if you place your hand over the throttle body does the idle improve? If it does you have a vacuum leak.
 
I have to agree with zora. It sure sounds like a vacuum leak to me. Did you remove the throttle body from the intake? If so, check that base gasket. If not, it sounds like it could be a leak around the intake manifold to me. But, I'm not an ASE mechanic. Just an old shade tree for over 40 years.
 
I did remove it but it got a new gasket and was torqued to spec. I have found a few loose fitting and I'm replacing those. We also sprayed around the intake manifold to see if the were any leaks but none could be seen.
 
Ok so with a hand placed on the throttle body she just dies. So I guess its not a vaccum leak it has to be fuel related at this point not sure what it could be. Doing a fuel pressure test today its time for another gas shower I guess.
 
So it appears that my fuel pump is disconnected from the line or is completly shot. Did a fuel pressure test and it has less than a pound of pressure. Lol I guess it was running purley on syphon before I did the rebuild and when I broke the fuel lines free it broke the seal. so the syphon couldnt keep up anymore. We also did a throttle body tune up which was good cause the old seals were dry as all hell and the reg was kinda worn out.
 
glad to hear you were able to track the problem down
 
Great news that you're back on the road again.
 
Good news!
I gotta ask. How does that explain the stuck 8-9 degrees advance? That threw me way off! Or is it still stuck?

"whenever I get her to run and check the marks she sits at 8-12 instead of 0 and this is with the advanced disconnect both connected and disconnected."
 
Ok so the pump was disconnected from the fuel line but was close enough that it would create a siphon. The last person that did the fuel pump was an idiot they bent the pump tubing,reused the old sock and didn't put the lines on right. I'm fully amazed that she was running before the rebuild. It is now timing perfectly at zero! Its amazing the difference when you actually have fuel pressure! It was honestly a last ditch effort to pull the tank.
 
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