lostsoul Posted March 20, 2017 Report Share Posted March 20, 2017 Hi,Setting up a Surge Tank ... want the lift pump to come on after 500rpm and be run by a solid state relay so there can be some speed adjustment.Can some one advise on the correct wiring diagram for this?I have AUX2 set as GP PWMThanks in advance. Quote Link to comment Share on other sites More sharing options...
Adamw Posted March 20, 2017 Report Share Posted March 20, 2017 How is the engine going to start if there is no fuel until above 500RPM? Quote Link to comment Share on other sites More sharing options...
lostsoul Posted March 20, 2017 Author Report Share Posted March 20, 2017 The FP in the Surge Tank will supply the fuel to start and run the engine, figured there was no need to have the "Lift" pump running until the engine was running. Quote Link to comment Share on other sites More sharing options...
lostsoul Posted March 20, 2017 Author Report Share Posted March 20, 2017 Ok this what I have ... 1 x Hella Solid State Relay with pins connected as follows: "87" = Fuel Pump "86" = ECU aux2 "85" = n/c "30" = switched 12v ... the Fuel Pump is earthed to the chassis.Problem is, as soon as the key is turned on the pump runs ... I want it run only if rpm is 500rpm or higher ... 2 reasons, 1 safety and 2 it is only a "lift" pump supplying a Surge Tank.I am picking I have the relay pins connected incorrectly but can't find any info that works .... any ideas ???This is how I have aux 2 configured. Quote Link to comment Share on other sites More sharing options...
Ducie54 Posted March 21, 2017 Report Share Posted March 21, 2017 Pin 85 should be connected to ground Quote Link to comment Share on other sites More sharing options...
Adamw Posted March 21, 2017 Report Share Posted March 21, 2017 I personally would have powered the lift pump relay from the main fuel pump relay then get rid of the >500RPM condition. That way the lift pump will at least still "prime" for a few seconds to ensure there is some fuel in the surge tank. I would have thought if you leave the car sitting for a couple of weeks the fuel will drain out of the surge tank and it will never start... krohelm 1 Quote Link to comment Share on other sites More sharing options...
Ducie54 Posted March 21, 2017 Report Share Posted March 21, 2017 (edited) The return line from the surge tank is at the top not the bottom so i cant return to the fuel tank. Not to mention most fuel pumps have a internal check valve This is the way i've setup mine using PWM lift pump. Edited March 21, 2017 by Ducie54 Quote Link to comment Share on other sites More sharing options...
Adamw Posted March 21, 2017 Report Share Posted March 21, 2017 The return line from the surge tank is at the top not the bottom so i cant return to the fuel tank. Not to mention most fuel pumps have a internal check valve Yes, I do understand how a surge tank works. Most lift pumps do not have a check valve, and most lift pumps are connected near the bottom of the surge tank. In most installs I see the surge tank is mounted above the main fuel tank. So the fuel in the surge tank will always want to travel "down hill" back to the main tank. The lift pump will slow down that travel back to the tank but I expect most would have enough internal bypass to empty the surge tank over a few days. Of course we are both making many assumptions here since the OP gave no info at all about his setup but I'm just trying to cover all bases. I suspect most users that run their car everyday would never see an issue with such a set up, but for instance some race car that only goes out once every 2 months may be a different story...I like how you have set up yours since the lift pump will still do a prime cycle. Quote Link to comment Share on other sites More sharing options...
Ducie54 Posted March 21, 2017 Report Share Posted March 21, 2017 I'm not going to argue the mechanicals and theory behind the surge tank. The OP was asking about wiring up soild state relays . No wonder why he went to another forum to find an answer. I tried to answer his question you did not, that is not a assumption. Quote Link to comment Share on other sites More sharing options...
lostsoul Posted March 22, 2017 Author Report Share Posted March 22, 2017 The return line from the surge tank is at the top not the bottom so i cant return to the fuel tank. Not to mention most fuel pumps have a internal check valve This is the way i've setup mine using PWM lift pump. Thanks for that ... Tried it with pin 85 earthed, still no joy ... I have seen a post of yours on this subject using a SSR p/n SY4086 so will give one of those a try. Quote Link to comment Share on other sites More sharing options...
Steve Posted March 22, 2017 Report Share Posted March 22, 2017 Maybe the relay is ruined. They dont like to be hooked up the wrong way. Quote Link to comment Share on other sites More sharing options...
lostsoul Posted March 22, 2017 Author Report Share Posted March 22, 2017 Yeah, that was what I was thinking so I am going to try the other one. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.