1985 Limited Edition 2022 Work Period

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derrick woods

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I think those models you could get both fuel injection or carb be nice if you could get rid of that fuel injection system and replace it with carbs earlier fuel injection was problematic
 
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Rednaxs60

Rednaxs60

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Thanks for the reply.

The '85 Limited Edition and '86 SE-i only came as fuel injected models. I have only read and seen one forum thread where an '85 Limited Edition was converted back to carbs.

These fuel injected models are a learning curve and do take a lot of forethought; however, I read more threads on carb issues. Carb parts are not as plentiful as one would like to think. The earlier carb models also have ignition issues, especially the ones that have been modified to aftermarket kits. I would say it's a toss up which is more problematic.

Aftermarket parts are readily available if you are willing to research the issue/part. The only part I have not been able to source an alternate for is the ECU. Have been investigating the Megasquirt or the Speeduino as an alternative.

The main issue with these FI models is the understanding of what to when there is an issue. A lot of us backyard mechanics do maintenance without fully understanding the issue or the ramifications of what we are doing.

Are carbs simpler to operate/maintain, maybe, but not from what I am reading on the forums.

These FI models work well with very little maintenance, but I'm after the 99.9% solution which means I delve into the minutia. I have time and will continue with my quest.
 
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Rednaxs60

Rednaxs60

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There are days when I want to make my '85 a boat anchor, but I knew what I was going to do, or have to do when I bought it. Got rid of an '08 1800 for this one. Hindsight, maybe should have kept the 1800, but that is history. Prefer fuel injection over carbs. The Mrs likes to ride the '85 too.

Have three bikes, 2014 Spyder RTL and a Royal Enfield Himalayan. Two I do what needs to be done, otherwise I/we just ride them. I see my '85 much like pidjone's Hunley, a work in progress, and a great learning tool.

Have thought of getting a carb model for a project. No room in the garage and the Mrs won't park her car outside. My half is quite full.

I use this forum and threads like this as my work journal, and I thank everyone for putting up with me. If what I find can help others with these FI models, time well spent.
 

julimike54

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Since I'm not familiar with the FI system, maybe I should ask my query differently. Presume the IAC is wide open, is there a way to verify that all the air is moving through (at proper volume) to the engine? IE could the passage(s) be partially blocked?
 
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Rednaxs60

Rednaxs60

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Could use an anemometer to measure the amount of air being drawn into the IAC system if you could find a small one. Used these to balance the ventilation systems on our destroyers.

During this work period, going down the investigation path, have just about ruled out all possible components/p[arts that could affect the engine operation and that I'm as close to the OEM factory specs as I can get.

I have done more research and reading to get a further understanding of the CFI system and how it operates, how the various systems interrelate.

Going to float a theory here from what I have read.

Checked the fuel pressure this morning, left the fuel pressure gauge attached overnight and it is at approximately 15 PSI matching atmospheric pressure so no more fuel movement because of the pressure in the fuel rail. There is a definite fuel shortage in the fuel rail because of this.

Turn the key to the ON position, the fuel pump is activated and the fuel pressure rises to the static pressure and fuel pump stops in 2-3 seconds. Fuel has been admitted into the fuel system, but the quantity is unknown.

The ECU has received all the sensor inputs it needs to successfully allow the engine to start at a fast idle because it is a cold engine.

Hit the start button and the engine starts, starts to go to a fast idle, but because of the fuel shortage and air in the fuel rail, the engine RPM starts to decrease. The ECU is monitoring the sensor signals and the signals indicate that the engine is not operating at the RPM required so the ECU starts to compensate for this by increasing the fuel injector opening duration to input more fuel into the engine to get it to operate at the RPM required for a fast idle. The engine timing will be adjusted to suit as well.

The additional fuel being injected into the engine results in a fuel rich condition, with the associated fuel smell(s) from the exhaust. This will continue until the engine RPM starts to increase, at which time the ECU will adjust the fuel injector open duration to suit the increasing engine RPM. Once the engine RPM is correct for the sensor input signals, the ECU will adjust the fuel/timing to suit, and the fuel smells on start should dissipate.

This condition remains until the fuel system is purged of all air.

So my thoughts going forward is that I have to eliminate, or significantly reduce the loss of fuel pressure in the fuel system.

Cycle the fuel pump on start 2-3 times. Short term fix if it works.

I will be having a look in the cylinders to completely rule out leaky injectors. I have spare fuel pumps on hand, so I will be changing the fuel pump. Do not believe the fuel relief valve is an issue.
 
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Rednaxs60

Rednaxs60

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Have hit the proverbial brick wall, again. Testing the fuel system regarding fuel pressure. As mentioned in my last post, tested my theory and I believe it is sound; however, the results are not as decisive as I would like. Have tried different scenarios to try and isolate the fuel pressure loss issue.

Changed out the fuel pump, no change. Have tried clamping off the FPR valve return to fuel tank, no change. No fuel leaking into the vacuum side of the FPR valve - indicates the internal diaphragm is good. No fuel leaking on the discharge side of the FPR valve when hose removed after shut down. Injectors do not appear to be leaking, no fuel residue in any cylinder - checked with small borescope. Injectors were cleaned, and flow matched at Witchhunter's facility. No connection leaks.

Have been looking into the FPR valve and even though it may seem good from testing, there is a possibility that after 37 years, the internal spring is week enough to allow the fuel system pressure to very slowly leak by without any discernible fuel showing (?). I did notice a strange sound when pressurizing the fuel system. It sounded like a small stream of fluid was being recorded back to the fuel tank. This only happened during the 2-3 seconds the fuel pump is priming the system. It was repeatable.

I thought about the fuel pumps the culprit. For the fuel pressure to bleed back through the fuel pump, and with the fuel shut off valve closed, the pressure would have to force the fuel in the system back through the fuel filter, across the engine for left to right side, down and through the fuel pump, and then out, up and through a closed fuel shut off valve, very enterprising.

Since there are only three components that could possibly allow fuel and to leak past, the FPR valve keeps popping up. Researched for a replacement, and found a thread on the Steve Sunder's forum. It is an FPR valve for a 1985 Honda Accord 1.8 litre engine, P/N PR86 or equivalent. It has been used on an '86 SE-i. It has a 2.7 bar rating.

This is one of those troubleshooting moments when I feel like a modern technician, troubleshooting by repair by replacement.

Open to suggestions. Cheers.
 
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Rednaxs60

Rednaxs60

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Fuel pressure relief (FPR) valve form an early model Honda arrived. The fuel return pipe had to be reoriented for use. Cut it off, clamp and JB weld used to secure the straight piece. Installed yesterday, works well at 2.7 bar. Have the fuel pressure gauge installed, the FPR maintains 2.7 bar static and dynamic, what you would expect. The fuel pump has a max pressure delivery rating of 65 PSI, good match. Honda specs have the static different from the dynamic, why - don't know.
 

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