Author Topic: Fuel injection systems  (Read 39719 times)

Offline Roger B

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Re: Fuel injection systems
« Reply #180 on: May 20, 2018, 06:42:38 PM »
Thank you both  :ThumbsUp:  :ThumbsUp:
I am still surprised how well the petrol injection system works, I think the horizontal engine runs better than with the carbs.  :headscratch: I am tempted to make a 360░ crankshaft and camshaft for my twin cylinder engine so I can try it with fuel injection using a single pump driven from the crankshaft. This would also work for Dave (Steamer's) Wallaby. 
If anyone else wants to try and build a system I am more than happy to support/help them  :)
Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #181 on: July 11, 2018, 07:56:27 PM »
As I said previously the Facet fuel pump I am using is not happy pumping into a closed system as it is really designed to work with a float chamber. All the mechanical petrol injection systems I am aware of circulate the fuel via a pressure relief valve. I bought a smaller gear type fuel pump designed for transferring fuel into the tanks of models. It is not continuously rated at full output but I am expecting I can significantly reduce the supply voltage so overheating shouldn't be a problem.
I then needed to make a pressure relief valve to operate somewhere between 0.7 and 1 bar. After playing with a few designs I decided to base it on the delivery valve of the fuel injection pump using a weaker spring. This puts the tank return at the top which will also help with bleeding the air out of the system. The body if 8mm square brass tapped M5x0.5 on the side and at the top to take the fuel inlet union and the valve cage/return union. The connection to the injection pump is via a long nipple soldered into the body.
Best regards

Roger

Offline Admiral_dk

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Re: Fuel injection systems
« Reply #182 on: July 11, 2018, 09:33:13 PM »
Still hoping that you solve all the problems with this project, but it is a bumpy road you travel here  :cheers:

Offline Roger B

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Re: Fuel injection systems
« Reply #183 on: July 30, 2018, 07:10:07 PM »
I shortened a 'trial' delivery valve to use as the inlet connector and then having received some 0.2mm wire springs I put it all together for a trial. Using the Facet pump it would hold 0.6 Bar but if I unscrewed the valve body 1 turn (0.5mm) it would let by so the spring looks about right. Now I need to mount the gear pump and try again.
Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #184 on: August 08, 2018, 05:54:47 PM »
I mounted the pump with a couple of angle brackets and used some of the existing pipework along with a couple of flexibles. I intended to use a bench power supply for the trials but the ones I had had a maximum output of 1A which was insufficient at the start (after some running time the current did drop). The back up plan was my sealed accumulators with the load bank to give some variation. I started with the 12V battery but as things eased off was able to use the 6V one.

5V 0.9A gave the expected 0.8 bar with some warming of the motor. Adding another 1mm washer under the relief valve gave 4.5V 0.75A and 0.5 Bar. The return flow was quite sufficient at these values. More voltage resulted in splashing out of the cap.
Best regards

Roger