I just put the vats bypass in and have power to the injectors. I do have the fuel pump working also. I just am not getting fuel into the engine. Ay thoughts. Background, The car sat three to four years due to vats and also had several owners. Seems first owners changed neutral safety switch and put in wrong etc. Then sat and sold. Next owners put in new fuel pump, fuel relay, and filter. Then I bought. I fixed neutral safety switch and put in vats bypass. Now I have fuel pump working and power to all 6 injectors. It will start on starting fluid but will not stay running without it. I drained the old gas and put in fresh. Could enough injectors be gummed up or clogged to cause this and how would I check? The fuel pressure regulator is good. I do not know much about fuel injection so I am at a loss.

 

The injectors will get "power" regardless of VATS check passing or not. The ECM grounds the injectors to operate them. Are you sure the ECM is getting the proper injector enable signal?

Best way to get rid of VATS is by programming an EPROM with VATS disabled.

 

Will it fire at all, or just crank and do nothing?
I've had 2 sets of used injectors short out on me. I've read the Multecs are notorious for that, even though their spray is superior to the Bosch on the 2.8. Because of toyr name I'm assuming you have a 3.1.

 

Check for a code 46... It's possible that there is a problem between the VATS and the ECM and the ECM isn't receiving the VATS signal and is shutting the fuel injection off.

 

I will double check the VATS bypass module but I seem to have no fuel to the injectors. I will start pulling it apart tomorrow evening and get more specific information on how far I am getting fuel. We need that to know what to do or go from there.
Thanks for all suggestions so far. Let me check this and then get further advice.
Yes it is the stock 3.1 and I am not getting any codes at this point.
My friend is getting antsy about swapping in a V8 but I do not want to do that yet. I want to take my time and build what I want the way I want.

 

There's only 2 things you need to do... Get a fuel pressure reading at the rail and check for a code 46. With the car having sat for so long and having a known history of VATS problems, I'd start with the code 46. The ECM will make you think there is no fuel to the rail, when there is no fuel in the cylinders but there is plenty at the rail (because the ECM isn't grounding the fuel injectors because of a VATS error... code 46). It's easy and you don't have to tear anything apart.

 

Worked on it some last night but it started raining. I found a blocked return line but will check further. Am going to double check the bypass for the VATS. I am not getting a code stored that I know off. How do I check for this code. I do not have a scan tool but assume you can jump two terminals and have it flash. I am probably wrong but if the computer is turning on the fuel pump then wouldn't the bypass be working properly?
Is there a way to check if the computer is grounding out the injectors properly? Can I put a test light on the ground side and watch for a faint light flash ( or is that wishful thinking)?

 

I've said it many times, but I'll say it again. The fuel supply (fuel pump) system is independant of the fuel injection system. Yes, with a code 46, the ECM still runs the pump just fine. With a code 46, however, the ECM disables the FUEL INJECTORS by not grounding them. You would need to connect the test light between the green and blue fuel injection wires and the positive terminal on the battery. The light will flash as the engine is cranked if the injectors are getting grounded.

You'll find the ALDL mounted next to the fuse panel (towards the right and to the firewall side). Jump the upper right terminal to the terminal immediately to the left of that and turn the key to the ON position without starting the engine. The radiator fan will turn on and the SES light will turn off before it flashes the trouble codes. The first code will be flash, pause, flash flash 3 times and then any other codes (in this case, you're looking for flash flash flash flash pause and 6 more flashes and then a longer pause before the code repeats 2 more times).

 

Thanks I will check both of these this evening if not raining to hard. I will be glad to know for sure. Otherwise code questions will keep coming up. I also find out if the bypass is wired correctly. I agree that it is possible to have the fuel pump working and injectors not. Also more information will help lead to the problem.
And thanks for verifying my thoughts on checking the injector power with a test light.
Thanks again

 

I checked the injectors as suggested and they are being grounded by the ECM. I also checked and no other blocked fuel lines. I also do not have a code being stored. I did however realize that the fuel pressure seems to be low. My often wrong manual says 34-39 psi. I will buy a gauge and check. It is possible that the wrong fuel pump was put in or a bad one. It is probably an Airtek. Will also plan on another new filter if I need to replace the pump. It seems to be less than half that pressure. Any other ideas on what to check while it is apart?

 

Fuel pressure should be between 37 and 47 PSI... It generally doesn't matter if the fuel pump is OE or not, but there is a part between the actual pump and the sender that often gets broken when the pump is replaced that should be checked for damage and proper seating on the pump.

 

If the pump is bad I will check everything in the sender unit closely. I am familiar with them. Have a pressure gauge now so will check tomorrow. I feel that this may be the problem but will check first. If the hose from the pump to the sending unit is broke or cracked it will also be low pressure so will check everything closely.
Thanks

 

Also, when you disconnect the pressure line at the fuel tank, get a bucket and a length of 5/16" fuel injection hose. After removing the fuel filter, put the hose on the pressure line coming from the tank, and blow compressed air (about 60 PSI) through the filter feed line to blow it out. Do the same with the feed line in the engine compartment and the other end of the fuel filter. Then, remove the fuel pressure regulator and blow the return lines out as well through the brass fitting in the middle of the FPR. That should clean out all of your lines. Don't forget to replace the strainer sock filter on the fuel pump as well and the fuel filter while you are down there.

 

That is all very good advice. I will do all of that. The fuel pressure check was at 9 lbs. Obviously to low to do anything. I am thinking about just replacing the regulator while I am there. I do not think it necessarily needs to be replaced but feel that I might be better with a little insurance before the upper intake is put back on. I already planned on the filter and pump strainer or sock. Hope to start the pump Sat afternoon or Sun. Sat morn is set aside to get some other parts from a salvage yard here.

 

OK, so I got the time to work on dropping the tank. The PO cut a hole over the top of the fuel pump. I do not mind that but cut it out entirely, do not fold it back. I will cut it out and make a peice to go over it later (just one more repair). The fuel pump was replaced but there is a broken steel line and regular fuel hose etc. there. Looks like I need to find a sending unit now as well as a fuel pump. This is a mess here and am glad I had to do this. Others may not agree with the way I do things but at least I can feel safe with what I do. This looks like an accident waiting to happen. Broke line right at the top of the sending unit and reg fuel line on all lines. The broken steel line is not repairable. An accident at fuel tank equals KABOOM (Oh Well who wants to see tomorrow anyways). Going to start searching for a sending unit.

 

It has been a while so an update is in order. I have gotten two used sending units and neither one has a working fuel sender. I am making a temp fix ( I can't believe I am doing this) to the old sending unit. At least the sender works somewhat. It can not be fixed properly that I know of. It will be safe but only temporary. I have a new Delphi pump ordered with a strainer. They should be in tomorrow. If this works to get it running then I will plan on a new sending unit before I put it on the road. Considering the PO cut the hole over the tank it is easy. This is only a temporary fix as I am running short this month now with all the other parts bought for it. Next month all my extra money can go toward getting it raodworthy assuming this gets it running. WIll post the results of the new fuel pump as soon as I know.

 

Yeah there's a right way and wrong way to cut a hole in the hatch floor; sounds like the Previous Owner did it the wrong way. I'm actually doing that to my car now; but I'm doing it the right way- using AN fittings (w/37 degree flare) and Earl's braided stainless hose between the pump and fuel filter (AN-GM fuel filter adapter is Earls # 991955ERL), and creating an access door using Dzus fittings (or rivet nuts, haven't decided yet).

I've had so many fuel pumps die on me thru the years that dropping the tank has lost its luster; I want it where I can change it on the side of the road if I have to (and you bet I'll be carrying a spare pump too).

 

How many fuel pumps have you had go? Just curious and wondering what the average life span of the blasted things is.

Personally, I plan on doing the above plus, hopefully, installing the fuel pump access cover from an 88-96 (possibly newer even) W-body. If I can get a cover.

 

TomP, Yes it was wrong. I always felt that if it is done that it should be cut completely out and a new piece attached over the top and preferably sealed. The PO cut it and folded it back. Then when done they just folded it back down all wavy. I finished cutting it out and will have to weld the floor there some but no big deal. I have never used AN fittings but will check into it. They Dzus fittings sounds like a very good idea and will look into something along those lines. Thanks for those suggestions.

As for fuel pumps going out I have put two in the Suburban I had and three in my pick up. I also had to make a repair on the Suburban so I dislike dropping a tank. You can jump on the patch panel in the Suburban and not know it is there. That tank is low enough I could screw the patch panel down with more than an inch of clearance between the tank and screw ends. On my pickup when it was at the shop because it wouldn't start they actually praised the ultra neat hole I cut and its nearly perfect centering over the pump. I keep a tool box in it so the hole is immaterial for usage. Still put a patch panel in though.

 

Stock one lasted until 1996 (changed it on 4th of July, thats how I remember). Replacement lasted 2 years later until 1998. Next replacement lasted until 2008, but had a bad drainback valve ever since I installed it (turn key off = pressure swings right back to zero). Funny enough, back then the fuel pumps were "lifetime warranty". Now when I look online, nobody has a lifetime warranty on a fuel pump anymore... I wonder why!

What's cool with the AN fittings is that I'm flaring the output pipe from the fuel pump a few inches from where it goes into the tank. Then I'm using hose straight to the fuel filter (with that adapter I mentioned). I used a dremel with cutoff wheel to cut the hole- basically I sanded a line in the sheetmetal until it cut thru. I was very worried about cutting into the tank. I've yet to cut the lines though!

I like the dzus or rivet-nuts b/c they wont leave any sharp edges to pierce the tank if anything happens.

That's cool about your hole in the Suburban. I was always against cutting a hole until I saw how flimsy the panel over the pumps were in other junkyard cars (with the access panels under the rear seats). Then when I got my daily driver I pulled the seat back (Mazda) and noticed how thin the access panel was. And then I found a few pictures on thirdgen.org of guys that made really neat and professional holes w/access panels, and figured if it's done right, it's OK to do.

 

TomP, What is the anti drain back valve? Where is it located? I may need to replace mine. I have the new pump and tried it. Am questioning it. It seems to still be low pressure but is higher that what I had so will get it put together with a new FPR and try another pressure test. The pressure with the old pump did bleed off. I thought back through the pump or FPR but I don't know. I probably should check into the drain back valve if it isn't in the pump as I thought.

 

No you're right, the anti-drain-back is inside the pump; like I said if it's bad, when the pump stops, the pressure drops immediately to zero.

If, after you turn the key back to off, the pressure slowly bleeds off, like, it's been 20 minutes and the needle's only moved a few PSI, then the anti-drain-back valve is OK.

If you have the GM manual then there's a whole pressure test in there (tests every component). What kind of low pressure are you seeing? (Low pressure could even be caused by a corroded electrical connection = the pump isn't getting a full +12 volts)

 

I don't have a new presssure yet the old pump had nine and bled back to zero almost right away. I was checking other things and getting ready to check pressures again. Had to do other things this evening when I got off work so will do more tomorrow (I don't know yet how to get around the annoying things that happen in life). I hate not being able to use my workshop/ garage. It gets dark so soon after I get home. I will get my workshop to use again sometime next month for sure.
The pump is in and hoses are on so am ready to check pressure again etc.

 

OK cool. Did you re-use the original pulsator (between pump and fuel inlet pipe)? The pulsator o-rings can leak after years of use; best bet is to use a short piece of fuel hose with those self-tightening clamps (the kind you squeeze with pliers). The pulsator doesn't quiet the pump noise much anyway.

Let us know how it goes...

 

I don't know why but I actually know what you are talking about. It is still there but doesn't have any external leaks. Could this cause a loss of fuel pressure? I do not mind the idea of bypassing it. I could put a pressure clamp hose on it easily. I took last night off sick but am feeling much better today. Am going to get another FPR tonight and install. Might also check pressure. Then I will see what will be next. I may have to check voltage at the pump to be certain.

 

I gor the new FPR put on and checked the pressure. It was after 1 small leak fixed, I didn't tighten a line, 38 lbs Max. It would only hold a static pressure of 20 lbs. Once the pump shut off it immediately dropped to 20 and held there. During this test I still have nothing going past the FPR so I still have a problem. The parts store said a Max pressure of 95lbs for the pump and about 43 for FPR with about 40lbs free flow pressure. Obviously my pump isn't up to these specs. Just for laughs I want to check the voltage again. Then I will talk to them about this.

 

Yeah at this point, if it's a new pump, new fuel pressure regulator, and you can't get over 20 psi with key-on-engine-off, I'd say it's voltage.

How did you check for max pressure?

 

I did a regular pressure test and got 38psi. Then noticed pressure bleed to 20 in a couple of seconds after the key off. At this point it stopped dropping noticably and stabilized. The 95 psi is just what the parts store gave for one of the specs on the pump.

 

You should go out and get yourself a couple pair of hose clamps (that pinch hoses closed, not the ones that hold them to whatever they're attached to), or get a hold of a couple pairs of vise grips. Pinch off the fuel hoses one at a time. If the pressure holds with the return pinched, the FPR or something is leaking. If the pressure holds with the pressure line from the pump pinched, there's a leak in there somewhere. If the pressure still drops with both lines pinched, you have a bad injector or 2 that are leaking.

Did you blow out the fuel lines when you had everything apart?

Check the wiring at the fuel pump relay... May be frayed and possibly shorting or losing voltage.

 

Thanks for the tip. I will try it as it will narrow down where the leak is and I can then deal with it. It will also be more information as to what else may be wrong. It did not seem to be leaking past the FPR but will still check everything in the exact order you outlined. I have done this to check the FPR before but never thought about it checking the injectors and pump also. And yes all the lines were blown out with compressed air while it was apart. I had found a blockage in the return line originally. I will check this while I check voltage and pressure again.

 

I checked for the bllled down and found it to be the FPR. Cycled it several times and it held at 40. The pump max pressure is at 62 actual.
Still a no start situation. Decided to get help and check timing while cranking and found water leaks from a broken port assembly on the front of the lower manifold. I also found water elsewhere. The bad news is it was plain water. After sitting for four years I am wondering about other possible issues from freezing. This was the first time for water out the intake port. This motor is either going to be swapped out for another V6 or a temporary V8 till I can build what I want.

 

Check for water in the oil... may look like a milkshake if the engine has run long enough. Other than that, there's a bunch of freeze plugs to check all around the engine block. If one of those has popped, you'll know, or you would have known by now. Definitely drain the radiator and make sure that the water comes out clear (you know what water does to iron compounds!).

That thing in the front of the intake is around $6 and takes only a half hour or so to replace, if you can get the old one out without breaking it.

Oh, and you can get a replacement FPR diaphragm at the parts store.

 

The oil is dark but not milky. The port is broke off about 1/4 inch from the intake. I would assume a freeze plug under a manifold but I do not feel like all that trouble when it still will not run. Another motor would actually be easier for me.

 

Only problem with replacing the engine is you can't be sure if the problem you have with this one would still exist...

 

I know I said I would swap to a carb but finding a carb setup isn't easy. However I had a thought about my fuel injection. To go back slightly the ignition switch is not original and the wires broke for the VATS anyways. I put a bypass in and though I have fuel pump working it will only work after I get oil pressure. I know it is supposed to pre presssurize the system but it doesn't. My question is could the bypass be hooked to the wrong wire on the computer? If so which is the right wire. I am told F10 and dark blue. I am hooked to F10 position which is dark blue. Could this be why my injectors seem not to be working? I have a ground signal but it may be weak and could it be some sort of feedback that the tester is picking up? Another thought to all those used to the computers on these cars is could I swap in a computer from a non VATS car to bypass the VATS?

 

Pin F10 is the correct input for the VATs bypass signal. I don't know of another MEMCAL that could be used. As they would be for a FWD with a DIS system. Ignition timing would be all wrong. Although one could be used for troubleshooting. Just open the EST/BYPASS connector to let the distributor handle the timing.

Fuel pump should do the run for 2 seconds at key-on. This is the ECM driving the FP relay for the prime. That is on pin A11 at the ECM. Pin D at the relay. Should get +12 volts for 2 seconds at key-on. Then again during & after cranking.

Wire color is DRK-GRN/WHT

It is important that the voltage is there again with cranking. This means that the ECM is getting distributor reference pulses. Which the ECM needs in order to fire the injectors.

So troubleshooting the FP relay and getting it operational is important to further troubleshoot why the engine isn't getting fuel.

If the engine still has the original Multec injectors they need to be replaced. You can ohm them out to see how many are less then 12 ohms. With shorted injectors this will prevent any of them from firing. Which will cause the symptoms you are getting.

RBob.

 

I fianlly have my workshop/garage emptied of a friends belongings and nearly put back usable. I also came up with a way to use my electric winch to get cars into the shop if not running. What can I say it is the lazy come out in me. As for the Firebird I disconnected the bypass and rechecked everything. My diagnosis is it wasn't doing anything. Everything still checked identical to what it was. So apparently the VATS was not bypassed. I wil triple check everything and also order all 15 bypass resistors. If that does not work then I have no choice but to swap over to carburetor as the only other way would be to send the computer in and have it reprogrammed for no VATS. As the V6 is only till I can get a V8 built I do not see the point of that.
I did finally find an intake, carburetor, distributor, and coil that will fit. They are all for no computer. I may have even gotten an air intake to clear under the hood but will worry about that later if I need to. I am still first trying to get the fuel injection working.