mellonman Posted July 3, 2012 Share Posted July 3, 2012 bit peeved to say the least just fitted a walbro gst400(400lph) to cope with my single nice and easy fit similar to the 255lph, but after fitting it started the car and it cuts out,though nothing of it just thought it was preasurising the system but after some time it still wont run, i checked the voltages to the pump so disconected the conector block and found to be a nice 9v happy days,so i then conected this to the pump and the voltage went? i know its making a circuit but i should still be able to read from it with the meter. anyway tapped into the wire while trying to start the car and found that i get a 6v while starting and then its drops to 0v and soon after cuts out. so im now thin king taht i need to do the 12v mod. i guess the motor is drawing to much current? do you bosch guys have to do any mods to the fueling wiring? help please i need to get to suprapod. Quote Link to comment Share on other sites More sharing options...
mellonman Posted July 3, 2012 Author Share Posted July 3, 2012 also i dont seem to be able to hear it prime. Quote Link to comment Share on other sites More sharing options...
David P Posted July 3, 2012 Share Posted July 3, 2012 Too much current draw for the fuel pump ECU, it will need a relay bypass and it's important that it's wired so it stops if the engine does. Quote Link to comment Share on other sites More sharing options...
mellonman Posted July 3, 2012 Author Share Posted July 3, 2012 i did think that might be the case i have seen this mod does anyone know if it would work and is safe will it still switch the pumps off in a crash http://www.mkiv.com/techarticles/12v_mod/12v_mod.htm Quote Link to comment Share on other sites More sharing options...
David P Posted July 3, 2012 Share Posted July 3, 2012 If you're stuck, use a short piece of 18amp wire to link T1 and FP I think. Quote Link to comment Share on other sites More sharing options...
mellonman Posted July 3, 2012 Author Share Posted July 3, 2012 i just started a 12v mod thread , and someone said it might be a poor connection i will double check tomorrow all the conections well the 2 at the pump as i had to in line connector the wires to the pump and thats all there is, Quote Link to comment Share on other sites More sharing options...
absz Posted July 3, 2012 Share Posted July 3, 2012 Without the 12v mod you should still see 9volts its seems you might have a bad connection,check the terminals in the grey connector plug there is also a connector plug in the spare tyre well which comes from the fuelpump ecu check that aswell. the multimeter is not a good way for testing live circuits try using a 12v bulb will give you a better indication of wiring connections. Quote Link to comment Share on other sites More sharing options...
richarde7927 Posted July 4, 2012 Share Posted July 4, 2012 Im running the same pump on standard wiring with no problems. Rich. Quote Link to comment Share on other sites More sharing options...
mellonman Posted July 4, 2012 Author Share Posted July 4, 2012 Im running the same pump on standard wiring with no problems. Rich. sweet that helps a great deal so i know there is a problem at the pump,well maybe. with out the pump connected i get a good 9v as soon as i connect it to the pump its drops out, i will double check connections but i have suspitions that the pump maybe defective, i will check what resistance i get throught the motor windings if all else fails Quote Link to comment Share on other sites More sharing options...
mwilkinson Posted July 4, 2012 Share Posted July 4, 2012 Sorry guys no help on the 12v power issue, but what are the Walbro 400 pumps rated to in terms of power? I was originally looking to go the twin Bosch 044 route, but am now tempted by a single Walbro 450, which states with a power upgrade to 13.5v will flow enough for 950bhp (Approx). I'm looking to run approximately 750 - 800 bhp max. This seems an easier option than staggered twin pumps but I doubt the claim and am concerned that the pumps will heat the fuel, like Jamiep experienced with the simultaneous running of both Bosch pumps. Quote Link to comment Share on other sites More sharing options...
mellonman Posted July 4, 2012 Author Share Posted July 4, 2012 If you're stuck, use a short piece of 18amp wire to link T1 and FP I think. just checked i think its B+ and FP i will test this latter when you say fit a relay would it be something like this Quote Link to comment Share on other sites More sharing options...
absz Posted July 4, 2012 Share Posted July 4, 2012 sweet that helps a great deal so i know there is a problem at the pump,well maybe. with out the pump connected i get a good 9v as soon as i connect it to the pump its drops out, i will double check connections but i have suspitions that the pump maybe defective, i will check what resistance i get throught the motor windings if all else fails IF the power is dropping out then you have a power feed problem you are getting voltage drop. if the voltage is only dropping to say 8volts then it could be a faulty pump loading the circuit. Quote Link to comment Share on other sites More sharing options...
mellonman Posted July 4, 2012 Author Share Posted July 4, 2012 it is the fuel pump ecu as when i but the short in b+ ,fp the pump starts working. i tested it again and i got a 12v prim voltage but as soon as i conect it to the fuel pump volts just go completely, so im forced to bypass the ecu i have just brought a relay to do it but not 100% on how its wired is my drawing any good? or anyone know where to find a drawing for the relay mod Quote Link to comment Share on other sites More sharing options...
Luxluc Posted July 4, 2012 Share Posted July 4, 2012 Quick question. What lph has 1 Bosch 044 and 1 Walbro GSS-341 in comparision with this new Walbro 400 lph?? Luc Quote Link to comment Share on other sites More sharing options...
mwilkinson Posted July 4, 2012 Share Posted July 4, 2012 Quick question. What lph has 1 Bosch 044 and 1 Walbro GSS-341 in comparision with this new Walbro 400 lph?? Luc From what I can find approx figures are: Walbro 208 lph Bosch 044 300 lph Quote Link to comment Share on other sites More sharing options...
Luxluc Posted July 4, 2012 Share Posted July 4, 2012 Roger that. I plan on going for twin 400lph, as my twin walbro setup will reach it's limits quite soon. Quote Link to comment Share on other sites More sharing options...
mwilkinson Posted July 4, 2012 Share Posted July 4, 2012 Roger that. I plan on going for twin 400lph, as my twin walbro setup will reach it's limits quite soon. That is some serious fueling. Do you want 800 Lph!!? A single 044 will run near on 700bhp. Thus one 400 could easily do 800 bhp? Walbro also do a 450 Lph pump. That is claimed to flow enough for 950 bhp. This would seem about right based on the figures for the single Bosch 044. Quote Link to comment Share on other sites More sharing options...
mellonman Posted July 4, 2012 Author Share Posted July 4, 2012 just checked i think its B+ and FP i will test this latter when you say fit a relay would it be something like this [ATTACH=CONFIG]154223[/ATTACH] well my diagram worked a treat happy days boosting to 1.3 at a lovely safe 11.2 Quote Link to comment Share on other sites More sharing options...
Nodalmighty Posted July 5, 2012 Share Posted July 5, 2012 well my diagram worked a treat happy days boosting to 1.3 at a lovely safe 11.2 This suggests to me it was your fuel pump ECU that was gradually failing and the current demand of the GST400 was the last straw. Your fuel pump could well have been fine all along, not that any of this really matters now Lyndon. Quote Link to comment Share on other sites More sharing options...
David P Posted July 5, 2012 Share Posted July 5, 2012 Too much current draw for the fuel pump ECU, it will need a relay bypass and it's important that it's wired so it stops if the engine does. Quote Link to comment Share on other sites More sharing options...
mellonman Posted July 5, 2012 Author Share Posted July 5, 2012 This suggests to me it was your fuel pump ECU that was gradually failing and the current demand of the GST400 was the last straw. Your fuel pump could well have been fine all along, not that any of this really matters now Lyndon. exactly what i thought after taking it for a spin, but to be fair the motor has done 150k miles so its had alot of use david P, good call dont worry i wont forget your comment Quote Link to comment Share on other sites More sharing options...
Luxluc Posted July 5, 2012 Share Posted July 5, 2012 That is some serious fueling. Do you want 800 Lph!!? A single 044 will run near on 700bhp. Thus one 400 could easily do 800 bhp? Walbro also do a 450 Lph pump. That is claimed to flow enough for 950 bhp. This would seem about right based on the figures for the single Bosch 044. After the engine build, I may be swapping between turbos. Therefore, I want the fueling spot on. I'm not sure 1x 400lph is enough ... plus they aren't that expensive, so I want to go the safe route. 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.
Note: Your post will require moderator approval before it will be visible.