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Car Forum / Volvo Cars / March 2006How to tight the in-tank fuel pump up to the assembly?
Hi, In order to investigate a fuel system problem (the car stopped after using 1/3 of the fuel in the tank), and after for the first time taking out the in-tank fuel pump for my 1988 240GL Volvo on this Sunday, I found out that the in-tank fuel pump was only connected to the assembly line by one cobble line (to one of the pump's electric connector). The fuel hose connecting between pump and the steel fuel line was completely broken and disconnected, and the pump can move up and down inside a plastic gasket without any constrains (luckly it did not slip into the tank)! After I removed the gasket from the assembly and took out the fuel pump, the cobber line connect to the pump was also broken. I think I can later on connect the cobber lines to the 2 electric connectors in the pump. And I also tested the pump with a 12-Volt electricity withouth problem, the pump works fine. I am going to buy a new fuel hose, but the question worries me now is that: how to connect the pump to the assembly? If I only put it into the gasket it can still move up and down, and it will be only physically connected by the fuel hose and 2 electric lines to the assembly. Is that correct? Or I missed something important that tight the pump up to the assembly? I search the Hayne's manual and Internet, but still could not find a explict description on how to tight the pump with the assembly? Can anyone shed any lights on this issue? I'll be greatly appreciated. Thanks very much. Regards Martin > Hi, > [quoted text clipped - 31 lines] > > Martin The pump assembly I'm used to working with on my 760 is different, I know, but on the 240s I seem to recall people saying it was held down by a castellated nut - a large nut with bumps like the top of a Spanish castle. Mostly I recall complaints about how hard it is to get loose. Are there threads around the pump area that would suggest that nut is missing? Mike > Hi, > [quoted text clipped - 31 lines] > > Martin I'm sorry - I didn't read the post closely enough. You are asking about the connection *inside* the tank. That thin bellows usually tears, causing the symptoms you have. I did what most people do, replacing the bellows (which is not available separately anyway) with a short piece of fuel hose and clamps at each end of the hose. Keep the hose short, because if it is too long it will jam against the bottom of the tank and block flow. Of course, a short hose will keep the pickup off the bottom of the tank and not allow the very last gallons of fuel to be used. Mike Hi Mike, Thanks very much for your reply. Just want to clarify the comments, do you mean that there is only the fuel hose that connects and tight up the in-tank fuel pump to the assembly (besides the 2 cobber electric lines to the pump's 2 electric connectors)? I am wondering if it is like that, the pump can move up and downs freely inside the gasket, the hoses will always have the "downside" pressure because of the weight of the fuel pump and it will "tear" off the hoses sooner or later? Thanks. Regards Martin > Hi Mike, > [quoted text clipped - 15 lines] > > Martin Yep, that's how it is. The idea is that the pump floats in the bracket, so the pickup sock can rest right down on the bottom of the fuel tank yet not be smashed against the bottom of the tank. Fuel hose is pretty strong, I think you'd break the plastic fitting on the pump before tearing the hose. Hi, Thanks for the ideas and suggestions. Then in that case I suspect that the fuel hose in my tank was a bad one since it was completed broken and torn off. The fuel pumps (both internal and external) were replaced by a mechanics several months ago. Does anyone know what the hose should be like? Thanks. Regards Martin > Hi, > [quoted text clipped - 10 lines] > > Martin The original was a thin, folded rubber piece that allowed the pump to move up and down. That is really too fragile and isn't available separately anyway. I used standard fuel hose (is that 6mm?) and a pair of worm clamps. If you take the pump to the auto parts store and say "I want a short piece of fuel hose to fit this" you will get something that works. I think the piece I used was something like 5cm long but I had to buy a foot of it. Mike Hi, Maybe this is a naive question, but if the goal is to pump the fuel out of tank, why does it need to let the pump to float on the surface of the gasoline and not just tight the in-tank fuel pump to the bottom of the tank? Unless it is required that the in-tank fuel pump can not be submerged into the gasoline? Thanks Regards Martin > Hi, > [quoted text clipped - 11 lines] > > Martin It doesn't float on the surface, it floats on the bottom of the tank. If the pump mount and tank dimensions were precision made then the bracket could be rigid, but things vary so the idea is to give the pump some slack so the pickup can rest on the bottom of the tank without smashing against it and clogging. Hi, I still do not fully understand how it works. If the in-tank fuel pump was connected to the fuel feed line (mounted on the assembly) by the fixed-length fuel hose, then how would it move up and down freely, unless the hose can be "dynamically" shortened or extended? Or another "explanable" way is that the pump should be tighted up to the assembly so that its pickup socket can be able to reach the bottom of the tank, then it pumps gasoline through the hose to the fuel feed line without moving up and down when the level of the gasoline in the tank changes. But it was not like in my Volvo, as there is a gasket which was mounted to the assembly and the pump was slided into the gasket and can be moved up and down. Possiblly there are some parts missing, as the fuel pump was replaced serveral months ago by a mechnics and I remembered after I ordered the fuel pump for him, he said that there was something parts was not fitted for that pump but he somehow "managed" to get it working. Am I missing something? Thanks. Regards Martin > Hi, > [quoted text clipped - 25 lines] > > Martin No - it sounds like you have it all there. After the repair the pump will no longer be free to extend to the bottom of the tank, so the last gallon or so of gasoline won't be picked up. Before the pickup filter sock was able to rest on the bottom of the tank, but now it won't. But as long as you don't try to get the last mile or km out of the tank you'll do just fine. Mike Thanks. I will buy the fuel hose to connect the pump to the fuel feed line. The length of the hose will be measured so that the pickup socket would be able to reach the bottom of the tank. Since the hose's length is fixed I will secure the pump to the assembly (sending unit) and won't allow it to move up and down. Are there any problem with this approach? Thanks Martin > Thanks. > [quoted text clipped - 9 lines] > > Martin No. If you're being that particular size the hose length with the tank about a quarter full, that way as it changes size during filling and heating you won't be far wrong from ideal a high percentage of the time. Bob  SignatureThe goal when driving is to miss the maximum number of objects. > Hi, > [quoted text clipped - 10 lines] > > Martin It rots out with age, rubber just breaks down like that. Just get a piece of standard rubber fuel line of the right diameter, IIRC it's 5/8", but take the prepump with you to the store. |
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