Engine Howell JP-1 (CA) EFI Kit troubleshooting

[dmented]

I installed a Howell JP-1 EFI Kit on my 1983 CJ7.. on start-up the engine keeps revving to the point i think it will explode.... I start it but can only let it run for two seconds before it reaches dangerous rpm's..... the butterflys are closed... i hope someone can help... Troy at Howell is out for a family emergency and won't be back for a week...

 

[TSB8C]

High revving is usually a vacuum leak. The throttle body has an IAC (idle air control) valve to control incoming air based on the temp sensor and to control the idle speed. If air is leaking from somewhere else (such as the adaptor plate for the throttle body to mount to the intake manifold) or other source, the ECM will attempt to feed more fuel to keep the air-fuel ratio in line. The other possibility is that the base idle has not been set properly using the adjustment procedure. From their troubleshooting guide:

8. The RPM on my engine does not come down when I
come to an idle:
• More than likely you have a large vacuum leak, verify that your system is
free from vacuum leaks.
• Check that all non used vacuum ports are plugged.
• Verify that the bolts holding down your throttle body are not protruding
through the bottom of the adapter plate causing the plate to lift off its base.
• Your ignition wire is connected to a battery source and not an ignition 1
source.
• The engine has not come to full operating temperature as of yet.
• Your thermostat is inoperable or opens at too low of a temperature. You
should be using at least a 180 degrees stat.
• Throttle cable or throttle on the throttle body is not coming to a complete
close. Throttle plate is binding in the throttle bores.
• The throttle plates are adjusted too far out, see procedure #10 for proper
adjustment sequence.
• IAC is not working, either faulty or there is a wiring issue.

 

[boney]

Assuming you installed this on a known, well running engine, I'd start with a vacuum leak. I'd start by checking between the throttle body and adapter plate. You may also have D/C'd the brake booster line on the intake manifold. It's just under the throttle body facing the left fender. There are 4 vacuum ports on my Throttle body. One on the rear (facing the cars rear) for the MAP sensor, two about center line on the front for the PCV/charcoal cannister and vacuum CTO valve/distributor advance. The fourth is on the front, off to the right side and is plugged.

If your throttle body is properly secured and not apparently leaking, disconnect the vacuum lines on the front and plug the connections at the throttle body. See if that helps. Alternately, you can use a pair of needle-nose pliers with short sections of hose slipped over the tips to temporarily clamp a vacuum line closed. This can be used to determine the individual offender if there is a leak somewhere.

Make sure your EGR valve is closed and not leaking.

Check your timing.

When starting the cold engine, the computer does not use the O2 sensor to make adjustments. Only the water temperature sensor and MAP sensor (according to the literature.) Don't mess with the O2 sensor for now, it's not in the equation. But do check to make sure the MAP sensor is getting vacuum and is mounted correctly.

Ensure the white wire is connected to the negative side of your coil. This sends the tach signal to the computer. As per the instructions, an aftermarket ignition may require a special filter.

Let us know what you find.

 

[Patrick]

If you purposely introduce a heavy vacuum leak on a good running fuel injected engine, it should never reach dangerous rpm’s as stated. But if the butterflies are not choking airflow correctly, then I can see this happening. We’ll see.

 

[dmented]

If you purposely introduce a heavy vacuum leak on a good running fuel injected engine, it should never reach dangerous rpm’s as stated. But if the butterflies are not choking airflow correctly, then I can see this happening. We’ll see.

 

[dmented]

all possible vacuum leaks have been investigated... there are no vacuum leaks.... on start-up it revs to over 5000 rpm's .. fuel injectors are delivering huge amounts of fuel and the butterflies are completely closed... i have isolated every possible leak and then reconnected each vacuum line one at a time to no avail.... disconnected MAP and throttle sensor at each test... frustrating!!!

 

[Patrick]

If you are at the installation stage, I would wait for Troy at Howell. You’ll have to be patient.

 

[dmented]

thank you... after all the tests and no results, i know i'll just have to wait... i hope that all is well with Troy and family... thanks again,,, i'l;l post again when i fix the problem!!!

 

[boney]

In the mean time, because these are things you're going to be asked by Troy to check, ensure that it's getting a proper RPM signal. Check your timing. Put a pressure gauge on the fuel supply and make sure you're not way over. If your pump is not the stock pump, or your return line is obstructed, then you could have problems. Fuel gauges are not expensive, and I promise, Troy will ask you what the pressure going to the throttle body is. Might as well be ready.

These are not overly complex systems. Dumping fuel means too much pressure or signal for too much fuel. Read on...

Have you tested to see what disabling the Idle Air Controller does? Pretty sure Troy is going to ask you to do this anyway... At the bottom of page 11 in the installation instructions, you will find in bold "Idle Air Adjustment Instructions". Skip the part that says "before....." and go to the numbered instructions on page 12. What you will be doing is closing, and eliminating the Idle Air Controller from operating until you plug it back in. It's easy to do and this will rule out that the computer is arbitrarily revving your engine by dumping a lot of air (and also fuel) into it.

1. If you have too much fuel (fuel pressure is too high) it should run rich and smoke black. My shade-tree observation suggests this is not the case, as revving real high requires enough air to get there.
2. In my opinion, you're now looking to see why/how/if you're getting too much air. This simple test of turning off the Idle Air Controller (it will be closed and out of the equation until you hook it back up) will see if the system, in the most basic of setups, will at least run reasonably without running away. It SHOULD idle at a reasonable speed without the IAC, assuming that everything else is connected correctly.
3. If it idles correctly then you know a few things and that will help Troy. Notice, that at the top of page 13, they want you to do all of this before calling Howell.

I have a friend that went through one of these systems part for part over the course of a long, long time. He installed a second hand system with no warranty and it ended up being an improperly installed RPM filter (from the factory, many years ago.) Troy will help you get to that diagnosis if you have to. My friends symptom was a surging engine, no matter what he did to solve the problem. This is why I've mentioned ensuring that the system is properly connected to the coil and you've taken proper measures for an aftermarket ignition if you have one. A bad engine speed signal really messes with the computer.

Sorry I've written so much. Don't give up yet, I feel like there are a couple more things you can do to help yourself out, or at least help Troy out when he is able to answer the phone again.

 

[boney]

Above- I said "not the stock pump." What I meant was "not the pump included in the kit." 10 minute edit limit was exceeded before I caught the mistake.

 

[dmented]

In the mean time, because these are things you're going to be asked by Troy to check, ensure that it's getting a proper RPM signal. Check your timing. Put a pressure gauge on the fuel supply and make sure you're not way over. If your pump is not the stock pump, or your return line is obstructed, then you could have problems. Fuel gauges are not expensive, and I promise, Troy will ask you what the pressure going to the throttle body is. Might as well be ready.

These are not overly complex systems. Dumping fuel means too much pressure or signal for too much fuel. Read on...

Have you tested to see what disabling the Idle Air Controller does? Pretty sure Troy is going to ask you to do this anyway... At the bottom of page 11 in the installation instructions, you will find in bold "Idle Air Adjustment Instructions". Skip the part that says "before....." and go to the numbered instructions on page 12. What you will be doing is closing, and eliminating the Idle Air Controller from operating until you plug it back in. It's easy to do and this will rule out that the computer is arbitrarily revving your engine by dumping a lot of air (and also fuel) into it.

1. If you have too much fuel (fuel pressure is too high) it should run rich and smoke black. My shade-tree observation suggests this is not the case, as revving real high requires enough air to get there.
2. In my opinion, you're now looking to see why/how/if you're getting too much air. This simple test of turning off the Idle Air Controller (it will be closed and out of the equation until you hook it back up) will see if the system, in the most basic of setups, will at least run reasonably without running away. It SHOULD idle at a reasonable speed without the IAC, assuming that everything else is connected correctly.
3. If it idles correctly then you know a few things and that will help Troy. Notice, that at the top of page 13, they want you to do all of this before calling Howell.

I have a friend that went through one of these systems part for part over the course of a long, long time. He installed a second hand system with no warranty and it ended up being an improperly installed RPM filter (from the factory, many years ago.) Troy will help you get to that diagnosis if you have to. My friends symptom was a surging engine, no matter what he did to solve the problem. This is why I've mentioned ensuring that the system is properly connected to the coil and you've taken proper measures for an aftermarket ignition if you have one. A bad engine speed signal really messes with the computer.

Sorry I've written so much. Don't give up yet, I feel like there are a couple more things you can do to help yourself out, or at least help Troy out when he is able to answer the phone again.

This is helpful... i'll check the fuel pressures in the morning and run through all your suggestions again... Troy will be back next Monday... thanks again!!!