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Discussion Starter · #1 ·
Hi everyone,

I recently purchased a 1996 geo tracker with 165k miles after getting an itch for a fun offroad toy. I have worked on my cars in the past and enjoy learning the quirks of each vehicle I buy.

Since I picked the tracker up it has had problems with running rich in general and stalling at idle. Once it gets moving and above 2k rpm it seems to be fine. The previous owner stated that it had not been driven in 6 months and was towed behind an RV in the past.

So far on the intake I have changed the air filter, removed and cleaned the, maf, throttle body, top half of the intake manifold (above the gasket), EGR and connecting pipe. There was a serious amount of gunk in the manifold but it is all clean now. On the exhaust, both O2 sensors are present although the cat has been removed.

When removing the intake I noticed that one of the ignition wires had been screwed between the intake and supporting bracket, pretty much cutting it in half. I replaced the spark plug wires, checked for spark on all cylinders and gapped the plugs to between 0.025 and 0.030 (as close to 0.028 as I could)

Now I have moved on to the fuel system There is a new fuel filter, installed by previous owner and I plan to run a cleaning cycle on the injectors. I picked up a fuel pressure tester and hooked it up to the connection that is about 12" below the rear of the intake manifold as I couldn't find an adapter to hook up to the front of the fuel rail. So, when I turn on the ignition to see the pressure, the gauge jumps to 100psi, holds for 3 seconds (while the pump is running) and then drops to between 40-50psi, where it remains for a good period of time. I was wondering what others see as fuel pressure when they run a test as this seems way too high and I'm wondering if it is what is causing me to run rich.

Thanks in advance for your help,
Rave
 

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Discussion Starter · #3 ·
I'll have to find an adapter to fit inline. Unfortunately none of the ones in the kit I have are the correct fit. Hopefully I'll get to it in the next couple of days.
 

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Were you able to correct the damaged injector wiring? If the ground wire for the injector was pinched, the injector would be full open. That possibly could have damaged the injector. Please don't take this as talking down, don't know what your knowledge level is...When the key is on, you have 12 volts to the injectors, and the ECM controls the ground to actuate the injector, and never just a full dead ground. Did any of the spark plugs look "wet" or fuel fouled?
 

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Fuel pressure factory spec is 34 to 41 psi.
 

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The fuel pressure is going to be the issue, you are correct it is way too high - I suspect the fuel pump may have been replaced at some point in the past.

If I recall correctly, the Ford F150 pump is a commonly used replacement, but there are at least two different pumps used with F150, and only one works, the other(s) cause the symptoms you're describing.
 

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Discussion Starter · #7 ·
Thanks for the input everyone.

@aquanaut20 I ended up just removing the FPR and hooking my air compressor up to it. It stopped clicking open around 40psi, so at least I know it is not jammed, it also held vacuum on the vac side.

@MountainManRobb No offense taken, I'm just a shade tree mechanic with a bit of experience, so I appreciate your input. It was an ignition (spark plug) wire that was pinched and I changed the full set. When I pulled the plugs they were all pretty black, so I suspect it has been running rich for some time. I was a bit surprised when changing the ignition wires didn't make any difference, given that there was essentially one missing.

@Bex thanks for the info. As explained above it seems to click off around 40psi.

@fordem thanks for the heads up, I'll take a look at the pump when I get a chance.

In the meantime I kept working as it's a fun car to wrench on. I found that the spark plug wires were off by 90degrees at the distributor, but when I put them in the correct position the engine wouldn't start. So... out came the radiator and the belts all came off. The cam and crank gears seemed correct but the keyway is badly worn. I intend to fix it as described on the Hwy83 channel and check the distributor for whatever error is most likely lying within. I'll keep the thread updated. Thanks for the help so far.
 

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Just for your info, the keyway fix was originally due to the same issue on a Mazda Miata. The original fix is here, so you can compare it with what Hwy83 does. The importance of the proper Loctite being used is…..important…lol. Good luck.
 

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Discussion Starter · #9 ·
Alright, time for an update.

A couple of things made me decide to jump in and take the head off. The keyway was worn, the distributor o-ring was leaking (and looked like it had been for quite a while), the poor running conditions/stalling continued and the engine has 160k miles. I figured it wouldn't hurt to give it a once over and replace gaskets while I was in there. Below are things that I took care of and some observations.

Checked compression (cold engine with WOT).
Cyl1:165, cyl2:168, cyl3:165, cyl4:157

Checked fuel pressure. 100psi with dead head prior to fuel rail (pump only), 55psi when fully assembled and checked at fuel filter connector.

Cleaned the intake from the throttle body to the head. It was caked up pretty badly and some pipes were almost closed completely.

Cleaned the injectors using a 9v battery and carb cleaner can with adapter.

Cleaned pistons, valves and maf.

Checked the block and head for warp (all ok)

Replaced gaskets: head, intake to head, mid intake manifold, exhaust, egr, rear coolant to block, valve cover

Set valve lash

When the car did run before I took the head off there was white smoke and liquid splatters coming out of the exhaust along with a smell of fuel in the exhaust fumes.

Once everything was back together I went to start the car. The battery cranked a few times but had been getting weaker, so I changed it for a new one. The new battery cranked once or twice and then wouldn't crank any more. I grabbed a 17mm and tried to crank the pulley by hand but it resisted. After removing the spark plugs the engine turned with the wrench on the crank, but cylinder 4 was full of gas that poured out the spark plug hole when the piston ascended. (when I disassembled the head originally, cylinder 4 was wet and the piston and valves were cleaner than the other cylinders)

When I cleaned the injectors I pulsed them open with a 9v battery while pressurizing them with a can of carb cleaner. They all reacted the same when I pulsed the battery. I am now wondering if there is a problem with the injector control. Either a pulse that is too long/continuous or a wiring short somewhere that is keeping injector 4 open. After I reassembled the engine I tried to start it maybe 10 times before removing the spark plugs and finding the hydrolock. I know that when the ignition is initially turned on it primes the fuel pump for around 3 seconds, so that alone could have filled the cylinder if the injector was open.

Are there any common problems with the ecu regarding injectors? Any weak spots in the wiring loom or common pinch points that may cause a short in the injector wiring loom.

Thanks in advance.
 

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  1. Disconnect the #4 injector and see if the engine will start, next
  2. Use a small low amperage light between the power and ground of #4 injector, does it flash or remain lite. ?
 

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If Philips comments above are followed, and after doing step 1 above and it locks up again, or is full of fuel, injector is stuck open,
 

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Your fuel pressure is way to high. Spec is 34 to 41 psi. And there’s a possibility that you damaged the injectors, even when attempting to ‘pulse’ with the 9v battery. And your keyway is ‘worn’??
 

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Discussion Starter · #13 ·
Thanks for the replies. I think I have got to the bottom of it and I can't help but laugh.

I disconnected the injector wires, removed the spark plugs and primed the fuel pump a number of times without cranking. Cylinder 4 filled with fuel, as before, so I assumed a bad injector. I decided to stick a chopstick into the other sparkplug holes to see if there was fuel in any if the other cylinders and lo and behold, cylinder 3 had some but 2 and 1 were dry.

It is worth noting that the car has been parked uphill on an incline in my driveway while I work on it.

After reading that the fuel pressure is way too high I pulled the fuel pressure regulator and decided to put my air compressor to the "fuel in" side to see when the diaphragm would open. Starting at 20psi, immediately the air came out the vacuum port, but none out of the "fuel out" pipe. I worked up gradually to 100 psi and at no point did the "fuel out" open. This means that the diaphragm is ruptured and a 55psi jet of fuel has been squirting into the intake manifold via the vacuum line on the fuel pressure regulator... No wonder it was running rough!

Anyway, an FPR has been ordered. I just hope the injectors haven't broken, but time will tell.
 

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Thanks for the replies. I think I have got to the bottom of it and I can't help but laugh.

I disconnected the injector wires, removed the spark plugs and primed the fuel pump a number of times without cranking. Cylinder 4 filled with fuel, as before, so I assumed a bad injector. I decided to stick a chopstick into the other sparkplug holes to see if there was fuel in any if the other cylinders and lo and behold, cylinder 3 had some but 2 and 1 were dry.

It is worth noting that the car has been parked uphill on an incline in my driveway while I work on it.

After reading that the fuel pressure is way too high I pulled the fuel pressure regulator and decided to put my air compressor to the "fuel in" side to see when the diaphragm would open. Starting at 20psi, immediately the air came out the vacuum port, but none out of the "fuel out" pipe. I worked up gradually to 100 psi and at no point did the "fuel out" open. This means that the diaphragm is ruptured and a 55psi jet of fuel has been squirting into the intake manifold via the vacuum line on the fuel pressure regulator... No wonder it was running rough!

Anyway, an FPR has been ordered. I just hope the injectors haven't broken, but time will tell.
Woohoo, not often they fail like that. FPR vacuum line is on the back end of the manifold?

Good find. Well done. Here's hoping a new one solves the issues
 

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As has been pointed out a number of times - the fuel pump pressure is excessively high - might that be what damaged the regulator?
 

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And now you have found the source of the extra fuel, it would be best to drain the diluted oil before you cause bearing damage..
 

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Discussion Starter · #18 ·
I have been looking around for a replacement fuel pump and honestly can't blame the previous owner for putting in a 100psi pump. All of the local auto stores show 100psi pumps as being compatible with the 96 tracker and a lot of the time the psi specs aren't even available.

O'Reilly:
Masterpro mpe16014: 100psi / 45 GPH

Autozone:
PFS Fuel Pump 5211005: 109psi / 54.2 GPH

Should a properly functioning FPR be able to deal with these pressure inputs and flow rates? Could anyone suggest the model number that they are using.

Thanks
 

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The fuel pump parts number for the 2 door 1996 Tracker/Sidekick is 15100 61AA1 or 15100 58B01 for the 4 door, as per the parts catalog.
I don’t know what O’Reilly is selling, but it would not comply with the factory parts number.
You should also be checking, for better results, using Suzuki. I assume you are the 2 door, 16v engine, correct??
 
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